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> ^ 1
THE
TELESCOPE
AND
MICROSCOPE.
By THOMAS DICK, LL.D.
REVISED BY D. P. KIDDER.
PUBLISHED BY LANB A gCOlT,
rOR TRB BUNDAT-SCnouL UXIOK 07 THE >fBTIVOD29T IPISOOfAL
CHURCH, 900 UULBERBlT-gT&EKT. *
JOSEPH LOXOKIMO, I^RlKT^'Vu
^ ^
s^
V
«.
ie0039
> •
CONTENTS.
PART I.
THE TELESCOPE.
PAGE
Section I. — ^Thb invention op the telescope 7
Section IL — ^Preluonabt definitions, and optical
nuNciPLBS to be recognized in the construc-
tion OF THE TELESCOPE. 18
Skotion in. — ^Description of common refracting
TELESCOPES 26
The astronomical telescope 26
The commou refracting telescope for land objects 80
The Galilean telescope 81
SbCTION 1Y. — ^TUS ACHROMATIC TELESCOPE. 33
Manner in which achromatic telescopes are fitted up
for astronomical observations 86
Section V. — ^Terrestrial ete-piecb for achromatic
TELESCOPES 38
Astronomical eye-pieces *)Ss
IMa^ona] eje-pieces *^
4 CONTENTS.
PAGE
Section VI. — ^Reflecting telescopes 45
The Newtonian reflector 46
The Gregorian reflector 49
The Cassagrainian reflector 50
Short accoutU of some large achroinatic and rejlectiiig
telescopes 52
Ibices of telescopes, of a moderate size, as made by the
London opticians 56
Section VIL — ^Disooyeries which have been made
by means of the telesoofe. 59
Discoveries in the solar system 61
The moon 61
The sun 62
Venus and Mercury 63
Mars 61
The new planets between the orbits of Mars and
Jupiter 65
Jupiter 6S
Saturn 69
Uranus 71
Neptune 71
Discoveries nnide hy the telescope in the sidereal heavens,.. 72
The distance and magnitude of the fixed stars 72
The milky way 73
Double stars 74
New and variable stars 76
Clusters of stars and the Nebulse.. 77
CONTENTS. 6
PAOK
Beflections suggested by the disooyebies of the
telescope. 80
The almighty power of God illustrated 80
Coincidence between the discoveries of the telescope
and the representations of Scripture 83
The cross of Christ a centre from which the Chris-
tian will survey the universe 84
Christian revelation viewed in connection with mo-
dem astronomy 85
PART II.
THE MICROSCOPE AND ITS OBJECTS.
Invention of the microscope 89
General description of mioroscofes 92
1. The single microscope 92
2. The compound microscope 101-
8. The solar microscope 108
4. The lucemal microscope 112
Objects to which the mioboscofb mat be applied 117
Jinimaleulet 122
1. The Monads 124
2. Animalcules in infusions of pepper 125
3. Eels in paste and vinegar 128
4. Animalcules in infusions of hay, grass, oats,
wheat, and other vegetable productions 129
6 CONTENTS.
5. P mciii > U om of some aiuBalcales of
The pkemomema of blood. 14^
OrealMtMm of the blood. 14S
DeKrijatiam ofAe partt of mme amaU amitmah m Mem w
Ae auerooeope 146
1. The flea. ^ 146
2. Mites 148
3. CnrioBS species of small cmstaceons animals 150
4. The stings of animals 152
5. The hairs of ft-nimalg 152
6. Scales of fishes 153
7. The dust on the wings of the moth and butterfly 154
8. The eyes of insects 155
Veg^ahle wbttaneet 158
1. The Carina of flowers 158
2. The leaves of plants and flowers 159
3. Transverse sectipns of plants 162
TutohfecU ^... 167
Hairs — the bat, mouse, dermestes 167
Scales on the wings or bodies of insects 169
Comparison of the ioorka of nature <md art. 170
Method of uamg miero9cope$ 173
REFLEcnoirs 176
■l^'- '>
THE TELESCOPE AND MICROSCOPE,
PART I.
THB TELESCOPE.
God has been pleased, in various ages, to guide
men to those discoveries which have enlarged
their views of his perfections, and increased their
knowledge and happiness. Among these dis-
coveries may be placed the construction and the
uses of the telescope.
Section I. — The invention of the telescope.
The telescope is an instrument for looking at
distant objects. Its name is compounded of
two Greek words, tele, at a distance, and scopein,
to view. {TrjXe, aKonelv,) By this instrument,
the most distant objects seem to be brought near
to the eye ; and many of those which are obscure,
and without its aid invisible, are clearly seen.
A terrestrial object, at the distance of six miles,
is as distinctly visible as if it were within eighty
or a hundred yards ; and wotlda, '^VkO^^^'^^ Vs^
^
8 THE TKLESCOrB. .
ages conceialed in the remotest depths of sfpoe,
or irhich shbe only as luminous points^iS the
heavens, are made so acci^ssible to our sight, that
thrar appearance, magnitude, and movements,
may he described and calculated.
It is difficult to determine to whom we are in-
debted for the telescope, and what is the precise
date of its invention. No discoveries have been
handed down to us, which would lead to the
conclusion that it was known to the ancients.
Before the end of the thirteenth century, glass
lenees were used to assist the eye in ohtainiug
distinctness of vision. There can be uo doubt,
also, that the celebrated Roger Bacon, who died
in 1292, was aware that lenses might be so ar-
ranged, as to magnify the appearance of objects
seen through them ; but there are good reasons
for beliering, that his knowledge was derived
only from reflection, and tliat he never carried
Ilia theory into practice. Whatever were the
ideas, or the eipeiiments of the learned, the teles-
cope was not much known before the beginning
of the seventeenth centui?. If, as some have
supposed, its existence may be traced back to a
much earlier period, its importance was not dis-
covered until an accidental circumstance brought
ronderful power into public notice. The
of a spectacle maker, residing at Middle-
^^i^wonc
burgh, in Holland, were playing in their fath(
workshop, and observed, that when they h«
between their fingers two spectacle glasHes,
some distance one before another, and looti
through them at the weathercock of the church,
it seemed inverted, but very near to them,
greatly inRreased in size. Having called the at-
tention of their fatier to this strange sight,* lie
adjusted two glasses on a board, supporting
them on two brass circles, the distance of which
from each other might be increased or dimiDished
at pleasure. Many persons visited Ms workshc
to see liis experiments, which afforded ami
ment, and awakened curiosity. To this iucidc
we may probably attribute the expresidon
Huygons, an astronomer of the seventeenth
tury, who described the telescope
invention."
For some time the oontrivance of the Middle-
burgh optician remained unimpro\-ed, and was
" The samo change in the appearauce of olueotB tc
be »een by atij one wlio haa (c1b3?cb at command. ~
a oonvex glasa or lens. Buppass of fourteen inohes t
eil distance, and another of two iochea focal distau
Jiold theia in a lltii) sixteen inches agunjBT, and In
thTOugh the glass of two inclwa fooua, and objeotB will
appsar inverted, and seven limes larger and nearer
than to the naked eye, that is. in the propartian of
fbttKeeu to two.
i
rch,^B
.(antdl^H
dlmk.^^^
tH will I
10 Tlin TELKSOOPE.
applied to no valuable purpose. At length,
about the year 1609, two workmen of the same
city, by giving to his discovery a new form, made
all the honor of it their own. Tlicse men, whose
naraes were Zachariah Jans, or Jansen, and Hans
Lapprey, or Lippersheim, are said to have beea
spectacle makers. One of them placed the
glasses in a tube, the inside of which he blackeced,
to prevent the glare, which would be occasbned
by the reflection of light from a bright surface,
and which would produce indistinctness of vision.
The other placed the glasses in tubes, sliding one
within another, to make the instrument portable
by diminishing its length. When Jansen had
completed his telescope, he presented it to Prince
Maurice of Nassau. The United Provinces were
then at war with Fmnce, and the prince, per-
ceiving the advantage which he might obtain in
the field over the enemy by means of this gift,
desired that its invention should be kept a pro-
found secret. But the time had now arrived when
the telescope was to be employed for nobler pvtr-
poses than those of war, and, ba the medium of
. most astonishing discoveries, to j astify what soon
afterwards was said of it, that the wit and indus-
try of man bad produced nothing so worthy of
his faculties. (Huygens.)
Before the time of Oalileo, who was born at
Pisa, in 1564, the obsei'vations which had been
made on the heavens were few and imperfect.
He has been frequently supposed to be the in-
ventor of the telescope, beeanse he was the first
who successfully applied it to astronomj'. In the
following passage, translated from a small work,
■written in Latb, which be publbhed in 1610,
under the title of " S'ldereui NKTirini" he con-
futes this notion, and. shows what prompted hie
first efibrts to make such an instmment. " Nearly
ton months ago, it was reported thiit a certain
Dutchman had made a perspective, throiigli
which many distant objects appeared as distinct
as if they were near. Several eiperimenta were
reported of this wonderful effect, which some be-
lieved, and others denied ; but, having had it
confirmed to me a few days after, by a letter
from Paris, I applied myself to consider the rea-
son of it, and by what means I might contrive a
like instrument, which I attained to soon after
by the doctrine of refraclions. And, first, I pre-
pared a leaden lube, in wLose extremities I fitted
two spectacle glasses, both of them plane on one
Bide, and on the other side one of them spheri-
cally convex, and the other concave. Then, ap-
plying my eye to the concave, I saw objects ap-
pear pretty large, and pretty near me ; they
peared three times nearer, and mne times
1
in surface, than to the naked eye. And soon
after I made another, which represented objects
abore sixty times larger; and at last, having
spared neither lahor nor expense, I made an
inEtcument so excellent as to show things almost
a thousand times larger, and about thirty times
nearer, than to the naked eye."
When Galileo had finished his best telescope,
he directed it first to the moon, the nearest of
the heavenly bodies, and saw it, as he Bays, at a
distance within two diameters of the earth. He
perceived on its surface tvfo kinds of spots, one
very clear, and the other dusky, resembling
clouds. He also remarked, that the boundary
between its dark and enlightened parts was ne-
ther a straight line nor a regular curve, but that
it was jagged and uneven, indicating the existence
of mountains and valleys. On esamining the aun,
he discerned several large dark spots, and ascer-
tained from their motion across its disc, that it
revoived round its axis in about twenty-sii days.
Jupiter presented to I'im new wonders. He
perceived three small stars close to the line in
which it was moving. By subsequeflt observa-
tion, he sow that they frequently changed then-
position, and sometimes disappeai'ed. After
watching them for a long time, he found tha'
they -were amaU planets, revolving roimd tht
laiger one, as the moon revolves round the earltk'
He afterwards discovered ti fourth eateltite.
Looking through his glass at Satum, he was as-
tonished to find it had the appearance of a planet
of large dimensions between two araailor ones.
They seemed almost to touch each other, and to
have their centres in a straight line. This obser-
vation was made early in 1610. GaUleo was
etill more astonished in 1612, to find that the
two smaller planets had disappeared. About
ten months afterwards tbey were again visible.
They soon assumed various shapes, and were
sometimes round, and then oblong ; at other times
semicircular, and then lunar, with horns pointing
, inwards, and growing by degrees so long, and bo
wide, ns nearly to encompass the
middle. To some the three appeared to be
jiuned, and to others to be disunited. Consider-
ing the imperfection of the first telescopes, it is,
perhaps, cot surprising that more than forty
years elapsed before any satisfactory esplanalion
cotdd be given of these phenomena. In 1650,
Huyg;ens published his dieuovery, that SntiuTi is
Burroundcd by an immense ring, the two lateral
parts of which had been erroneously supposed
to be two Binaller planets. In his desoriplion
("Systema Satumium") of it, he established
the position of the ring, ani exi
m
ite.. ■
ider- ^^B
14 THB ■I'BLESCOi'E.
of its occasional disappearance, and of the dif-
ferent forma under wbich it is seen. Venus waa
the next object wMch. engaged tbe attention of
Galileo. He observed this planet when near its
superior conjunction. At first it looked nearly
globular ; shortly afterwards Its phase was gib-
bous, or defieient in roundness ; it quickly became
lunated, or like a half moon, and then it dwindled
into a slender crescent, like the moon when three
or four days old. From these observations he
coDcluded, first, that the planets are opaque
bodies like the earth and moon, deriving all thor
lights from the sun ; and, secondly, that Venus
moves round the sun, and not, as was geuerally
imagined, round the earth. He then examined
the fixed stars, and beheld many, invisible to the
naked eye, nearly as large as those of the first
and second magnitude. Within the range of
the Pleiades, he counted no less than Ihirty-sis
stars, and almost as many in the constellation of
Orion, which are not visible to the unaided sight.
Prsesepe, which looks but a dim speck in the
sky, he perceived to be a cluster of forty stars,
and the Galaxy, or Milky Way, to be an innu-
merable multitude, powdering* the heavens ivilh
° " The gulttKj, that milky way,
Which nightly, as a circtiue loue, thou Meat
Poirdtr'd with stans." Mii,tob.
Uglit. The doubts of former philosophers re-
•pecting thb remarkable tract were at once solved,
' many of their speculations respecting it were
•kown to be scarcely less nhsurd than the fables
of the mythologists.
Intelligence of tfao discoveries of (JalUeo ra-
'jiidly spread throughout Italy and other Eu-
lopean countries. His book, already mentioned,
«Blitled " Sidtreut Nundug," produced an ex-
tiacM^nary seusation amon^ the learned. His
•tatemente were opposed to tlie philosophy of
Anstotte, and that was a sufficient reason with
many for their rejection. Some endeavored to
NftBon against hb facts, but others satisfied
with asserting, that such thin,
and could not possibly be. The prinoipat^
Hufeasor of philosophy at Padua, lest he should
)e convinced of their reality, refused to look
lltroi^h the glass of Oahleo. Martin Horicey,
ither of his opponents, is reported to have
1 to Kepler,* " I will never concede his four
Miltou riaitcd Galileo, and entertained the liigheat
l^idon of his phiiuaopb;, to nhicL he mokes some
bwutiful allnsiooa in his " Paradise Loil."
An able mnthematiciaii and aatrgnomer. Ro waj
I at Weil, in the dnobj of Wirttmberg, in IflTl,
died in ItiUO, Between him and Oalik>o tlw ,
mest frieadsbip aubsiated.
new planets to tbat Italitin from Padua, tliough 1
I should die far it ;" tmd in n book wbich he
published he solemnly decliired, tbat he did not
more surely know that he had a soul in
body, than thnt reflected rays were the entire
cause of Galileo's errors. Sizzt, a Florentine
astronomer, reasoned in this way: "Tiierc are
seven windows given to animala in the domicile
of the head, through which the mr is admitted
to the rest of the tabernacle of the body, to
enlighten, warm, and nourish it ; two nostrils,
two eyes, two ears, and a mouth; so in the
heavens, or the great world, there are two fa-
vorable stars, two unpropitious, two luminaries,
nnd Mercury alone undecided and indiSerent.
From which, and many other similar phenomena
in nature, such as the seven metals, we gather
that the number of the planets is nteenaarily
seven. Moreover, the sateUites are invisible to
the naked eye, and therefore can eiejt no in-
fluence over the earth, and therefore would b6
useless, and therefore do not exist." An agree-
able contrast to this senseless bigotry is presented
in the conduct of the senators of Venice, who
were eminent for their learning and palriotbm.
They invited Galileo to their city, to make a
trial of his new insti'ument in their presence.
Having complied with thuir invitaticm, one fine
THE TELESCOPE.
bight, neither cold nor cloudy, he erected his
telescope on the top of the tower of St. Mark.
Jupiter was shinbg brightly on the meridian,
the moon wus displaying its silver horns towards
the west in the form of a crescent, and Venus
was in full sjikudor in the same direction. The
senators gathered round the astronomer. Jupiter,
with its three satellites, the fourth being eclipsed
by the body of the planet ; Venus, at its farthest
distance from the sun, not a completely illu-
mined sphere, but one-half obscured ; and the
crescont of the moon, with its internal moun-
talnous -looking border, passed in succession un-
der their review. The senatoi's acknowledged
the truth of Galileo's discoveries, and alternately
poured upon him their compUments, and pressed
Hm with their inquiries. When he had answered
all their questions, he delivered a long lecture
to his distinguished auditors on the true system
(rf the universe. He showed that die ancient
system of Piolemy could not be reconciled with
the motions of the heavenly bodies, and that
the changes of day and night, the revolutions of
the seasons, the precession of the equinoxes, and
other phenomena, could only be explained on
the theory of Copernicus. That night was fatal
to the system of the ancient schools, The ad:
mirable discourse of Galileo camei torn
to every mind, The Venetian noble
ledged the pei-fect agreement of all thoy had
Been ■with the Copemicnn system.* From this
time it began to obtain credit throughout Eu-
rope, and the improvement of the telescope
became important to all who appreciated these
early fruits of its invention.
Section II. — Preliminary dejimtionit, and opti-
cal principles to be recognized in the construe'
tion of the telescope.
It b not necessary to enter iuto what Ts ab-
struse in optical science, in order to understand
the general principles on which a telescope is
constructed. But there are certain facta re-
specting light, and it« I'efractions, rcBectJcinH,
and their effects, of which some information may
be useful.
Light is an ethereal matter, distributed
throughout the universe, and rendering per-
ceptible to the eye Bcenes and objects, at once
" Copernioua was bom towarils the close of 0»
fifteeuLh centarj, at Thoni, in Pruasia. In his ty»-
tern he mode the sun the centre, about whioh the
planets reTolve at difTercDt distftsces, anil vith dif-
ferent degiTCB of Tolocitj. Above Ihe plnneta he
placed the BtBrry hcuvciia. whiuh are boundloB and
immeuurable.
the nearest and the most remote. It is essential
to life and happmeas. Wkliout it, creation
would be lifeless and unadorned. Like a per-
vading spirit, it animates what it reveais. It
faas become associated in our minds with order,
lieBuly, and goodness. It is so glorious, that it
is said to be the "garment" (Psa. civ, 2) of the
Almighty. It is so pure, that it is an emblen
by which He himself is represented. 1 John
It is so transforming, that light ia the written
name of that new creation, which It ia the wodt'
of the Holy Spirit to acconnplish in the heart of
man. Ephes. v, 8.
As the properties of light form the foundatioti
of the structure of the telescope, some of these
may be briefly stated. 1 . Light emanates or
radiates from luminous bodies, when passing
through the same medium, m a fitralifkt lint.
This ia proved fay the impossibility of seebg
light through bent tubes, or small holes pierced
in metallic plates, put one beliind another, unless
the holes be placed in a straight line. 2. The
particles of light are almost infinitely small. Dr.
Niewentyt computed that more than six billion
times as many particles of light flow from a
candle in one second of time, as there are grains
of sand in the whole eartlij supposing each cui^
incli of it to conlaiu Dn-e- niffi'tfnt.
1
.1^1:
I
T
moves with amadng velocity. It tmvels a
llie earth's orbit, a space of 100,000,000 of miles
in extent, in the course of sixteen and a half
minutes, or at the rate of 192,000 miles every
second, which is more than a million Umes
swifter than a cannon ball flying with its utmost
velocity. 4. Light is sent forth in all directions
fifom-evcry visible point of luminous bodies. If
we hold ;i sheet of paper liefore the sun, we
shall find that the paper is illuminated in what-
ever position we hold it, provided the light is
not obstructed by its edge or any other hotly.
5. It is by light reflected from opaque bodies
that most of the objects around us are rendered
viable. When a lighted candle is brought into
a room, not only the candle, but all the other
bodies in the room become visible. In like
manner, the light of the sun falling upon the
moon and planets, which are opaque bodies, is
reflected from their surfaces, and renders them
visible to oiu' sight.
When the ravs of light continue in any me-
dium of uniform density, tbey proceed in straight
lines, but when lliey pass Miqutl;/ out of one
medium into another, which is either more dense
or more rare, they are refracted towards the
denser medium, and this refraction is more or
|H| aft the rays fall more or less obliquely on
TELESCOPE.
refraclisg surfaoe which divides the mediunnB.
This may be illustrated by fig. 1, where b o is
the incident ray which falls upon the medium
N o, which suppose to be water ; c b is the re-
fracted ray, d a the perpendicular, a a the sino J
of the angle of incidence a o d, and n r the sine J
of the angle of refraction e c e. Now it b a
|iroi>oeitioii in optics, that the gine a d of the
angle of incidenco a c d, is m a given proportion
to the sine h b of the angle of refraction o o e.
Th« ratio of the shies is as four to three, when
tie refraction is made out of air into water; that
iSiAoiatonaas four to three. The angle
which the incident ray makes with the perpen-
, dicular is called the anffle of incidence, and the
angle which the ray makes with the same per-
pendicular after it eaters the medium, is called
the angU of refraction. If a ray of light n ^~
22 THE TELESCOPE.
n
were to pass from air into water, or from empty
space into air, in the direction m c perpendicular
to the plane n o, which separates the two me-
diums, it would suffer no refraction, because one
of the essentials to that effect is wanting, namely,
the obliquity of the incidence.
It is to the refraction of light that we are in-
debted for the use of lenses to aid the powers
of vision. A lens is a transparent substance,
usually glass, having two surfaces, either both
spherical, or one spherical and the other plane.
A convex glass is thick in the middle, and thin-
ner towards the edges. A concave glass is thin
in the middle and thicker towards the extremities.
Of these there are various forms. In the annex-
ed fig. 2, A is a plano-convex, b a piano- coii-
cave, c a double convex, d a double concave, s
a meniscus, or concavo-convex, which is partly
convex and partly concave, the convex side beii^
a portion of a smaller sphere than the concave.
The rays which proceed from visible objecte
are either parallel, converging, or diverging.'
Parallel rays are those which are equally dia^;
tant from each other, as those which proceed
from the sim and planets, and from distant ter-
restrial objects. Converging rays are such as
approach nearer and nearer in then* progress to
a certain point where they unite. Diver^ng
THB TELESCOPE.
23
Fig. 2.
Plano-convex.
Plano-concave.
Double convex.
Double concave.
Meniscus, or concavo-
convex.
rays are those which continually recede from
each other, as the rays which proceed from near
objects, such as a window in a room or an adja-
cent house.
When a convex lens, whether piano or double
convex, is placed opposite to any object, the
rays of light which pass through it form an
image or picture of the object in its focus, if a
paper or card be placed to receive it. Let l n,
fig. 3, represent a double convex glass, a c its
axis, and o b an object perpendicular to it. A
ray passing from the extremity of the object at
o, after being refracted by the lens at f, will
pass on in the direction f i, and form an image
of that part of the object at r. In like niitnner,
B t M is the axis of that parcel of rays which
proceed from the extremity of the object d, and
their focus will be at li, and all the points of the
object between o and b will have their foci be-
tween i nnd m, and an image of the whole object
o B will be depicted in an inverted position, be-
cause the rays cross at c, the centre of the lens.
This may be illustrated by experiment. Tabe a
coiivex glass of eight or ten inches focal dis-
tance, a reading glass, for example, and holding
it at its focal distance from a white wall, m s
line with a gas lamp or burning candle, the flame
of the candle or lamp will be seen painted on
the wall in an inverted position. The fact novr
staled is an important principle in opiics, and
forms the foundation of the camera obscum and
of the telescope.
The property of forming exact representatJons
of the objects from whence its rays proceed is
■mfi TELESCOPE.
possessed by light, whether emanating direc^
from the sun, or reflected from the objects it
illuminates, or coming from bodies artificially/
enlightened. This property ia hght is not p
liar to the system to which we belong,
were, our field of vision would Lave beep'
paratively limited. The telescope worild have
been useless for the observation of.tfioae distant
stars, which are the suns of otbeHyst«ma beyond
our own, and we should linv'e remained in pro-
found ignorance of worlds, " in number beyond
number," which now "declare" to iia "the
glory of God." In this point of view, we can-
not regard as accidental an inveation which has
made us better acnuainted with his omnipotence
and wisdom in the existence and arrangements
of the universe. It reveals to ua hia providen-
tial care displayed in all the departments of
nature, In every ray of light it teaches us the
lesson that " God is love." It leaves us, how-
ever, to learn from another source the highest
manifestations of that love. The Bible alone
can tell us that " God so toved the world, that
he gave his only begotten Son, that whos
bcUereth in him should not perish, but 1
r everlasUnglife." John iii, 16,
Before describing the structure of a ti
may be proper to state the manner a
\
the fooal diEtance of a convex lens. Le«^
fig. 4, be a convex lens, and c d parallel
proceeding from the sun ; those raya, afterpaai
ing through the lens, will converge to a point
Hold the lens opposite to the rays of the svo
and observe where the rays converge to a erne
spot as at e. This spot is the image of the sv
formed by the lens ; measure the distance b
tween the lens and the spot; it is the focal di,
tance required.
Section III. — Description of common re/ractin
telescopes.
There are various kinds of refracting tel<
scopes, which we shall describe in their orde
commencing with that which is the most simpl
and most easily understood.
1, T/ie astronomical telescope. — Theonlypan
essential to this telescope are two lenses, a
THS TELESCOPE. 2*1
Fig. 5.
^L^MMtfMtfS^
M
and £ Ty fig. 5. A d is the object-g^M, and
E T is the eye-glass. Let o b be ^/distant ob-
ject, from which rays proceed jeroarly parallel
to A D, the object-lens. The rays passing through
this lens will form an image of the object in its
focus at I M, and as the rays cross each other it
will be inverted, e y, the eye-glass, is placed
exactly at its focal distance from this image, and
must be of^a much shorter focal distance than
the object-glass. The magnifying power in this
telescope is in the proportion of the focal dis-
tance of the object-glass to that of the eye-
glass. Suppose the object-glass to be of twenty-
four inches focal distance, and the eye-glass one
inch, the magnifying power is then as one to
twenty-four ; in other words, it makes a distant
object appear twenty-four times nearer, and
twenty-four times larger in size than it is to the
naked eye. If the eye-glass had been one and
a half inch focal distance, the magnifying power
would have been only sixteen times. Through
this telescope all objects appear inverted, like
the image at i m. This telescope was much in
use by astronomers in the sevciv^e^tLXXi «x^^.
28 THE TELESCOPK.
eighteenth centuries. In order to obtaia ^ ^
dderable magnifying power, it was soorke^'
m^e more than one hmidred feet long ; anr
it was found inconvenient to have a tube of
length^"tt^ telescope was used without one.
high poleVwas erected, the object-glass
placed at th^op of it, and capable of b^^I
turned in every \direction by a cord whfcfi
descended to the station occupied by the ob-
ser^-er, who held the eye-piece at the height
of his eye, resting it on a pedestal. But these
long instruments are now entirely superseded by
the invention of achromatic and reflecting tele-
scopes.
A telescope of the kind described may be
easily constructed, and at a small expense. Pro-
cure a double convex lens, about thirty-six
inches focal distance, place it at the end of a
Fig. 6.
BO
tube, as at a b, fig. 6 ; at thirty-seven inches
distance from this glass fix another, c d, whose
focal distance is one inch. This glass must be
fixed in a separate shoil; tube, e f, which should
be made to slide backwards and forwards in the
large tube, for the purpose of adjusting the
B TELESCOPE.
focus of the telescope to the eye. Such a tele-
Bcope will magnify objects in the proportion of
one to tbirty-aix, or thirty-six times, and will
show the spots in the sun, the shadows of the
mountains and cavities in the moon, Jupiter's
satellites, the crescent of Venus, and otiier celes-
tial phenomena. In constructing such a tele-
scope, the following particulars require to be
attended to ; — 1. The aperture, or opening which
lets in the light at the object-glass, should not
exceed one incli in diameter, otherwise the image
of the object will be somewhat confused.
2. There should be a hole or aperture in th«
focus of the eye-glass rather less in diameter
than the breadth of the cyc-glass, for the pur-
pose of excluding .the exttaneous rays. Were a
telescope of this kind to be constructed with an
object-glass six feet focal distance, the eye-glass
would require to be one and a half inch focal
distance, and the aperture of the object-glass
one and a half inch diara«ter, and the magnify-
ing power would be forty-five times. Were the
object-glass ten feet focus, the eye-glass would
require to be one and nine-tentha inch focus,
the aperture one and seven-tenth^ inch, and
magnifying power would he siitj-three timt
Were the object-glass twenty feel focus, the
glass would be two and a UaVl WVa* Wraa-
ile-^n
ithe
ould^^l
I
1
jiperLwe two aiid four-tentlis, and the m
ing power would be eighty-nine times,
fonnd, that in order to magnify twice as maeh
Bs before, with the Batoe light and distinctnesB,
the telescope must be lengthened four times; to
magnify three times as much, nine times i fojle
times Hs much, siiiteea times ; that ia, suppb^ft
telescope of three feet to magnify ihirty-mi
&tiea, in order to procure a power four times u
greatj-or one hundred and forty-four times, we
muBt cjctend the telescope to the length of forty-
eight feet, or sixteen times the length of the
other.
2. The common refraclijfff' tcleacopf for lattd
olgeeta. The telescope just described, in coo-
sequence of its shon-ing every -^lAject m an in-
verted position, is not fitted for land objects.
In order to adapt it for terrestrial objects two
Additional eye-gkssea are req.nired. In fig. 7. lei
o B represent a dbtant object, i. k the object-
4fcl-¥l^.-
^^'
glaw which forms the image of i m in an inverted
poeition ; let e e represent another glass placed
M its focal distance from this image, as in the
' \
THE TBLBSCOPE. 31
V^ .otaical telescope, and f f a second glass,
'^Sced at twice ite focal distance from e e. By
this glass (f f) a second image is formed at i m,
contrary to the first image i m, and, consequently,
erect. This last image is viewed by the third
lens, a G, in the same manner as the first image
I M would be viewed by e b. All these eye-
glasses are understood to be of the same focal
distance, and are placed at double their focal
distance from each other. Such a telescope
represents land objects in their natural positions.
But this arrangement of glasses is different from
the eye-piece now adapted to achromatiq tele-
scopes, of which we shall afterwards give a short
description.
3. The GcdiUan telescope, — This telescope con-
sists of two glasses, a convex glass, c, next the ob-
ject, and a concave, k, next the eye, fig. 8. Let
Pig. 8.
I D represent rays proceeding from an object ;
tliese rays would converge to their foci, and form
m inverted image at f, if they were not intercepted
by ^ ooikoaye lens k. But tVfi& \«c& \a^\s^% ^
32 THi: TELESCOPI.
double concare, occasions the rays to <ii'v»n
more than before, so that the rays d i ^^aruitu
from the object, instead of converging to j^ jv
made to proceed parallel to o h, and it is para
lei rays that produce distinct vision. The coi^ '
cave lens, k, is placed as much within the foc^^
distance of the convex, c, as is equal to its ow^
focal distance, and the magnifying power, ai
formerly, is in proportion to the focal distance
of the object-glass to that of the eye-glasa
Thus, suppose the focal distance of the objeotf
glass to be twelve inches, and that of the con-
cave eye-glass one inch, the concave must b6
placed at eleven inches from the object-glasi^
and the magnifying power will be as one to
twelve, or twelve times. . This was the land of
telescope constructed by Galileo, and with which
he made his astronomical observations. Objects
are seen through this telescope in their natural
position, and very distinct, even more so than ii
other telescopes ; but the field of view is so very
small that its use is almost exclusively confined
to the common opera-glasses. A good telescope^
however, can be made on this principle capabla
of showing much to interest the observer. If
we take a convex lens, forty inches in focal dis«
tance, we may apply to it a concave lens of onl^
one inch focal distance, at the distance of thirty!:
lune inches from the object-glass, and the mag-
nifying power will be forty times, which will
show us Jupiter's satellites, the crescent of Ve-
nus, and Saturn's ring. There is some difficulty
in finding on object with this telescope, and only
ft pnrt of the sun and moon can be seen tbrougti
it at one time.
Skction IV. — The achromatic teleseopc.
The common astronomical refracting telescope
was very imperfect, and "was also so unwieldy
that its use .was attended witli much trouble and
inconvenience. To obtain a considerable magni-
fying power, it was found necessary to increase
its length to siity, eighty, one hundred feet, and
upwards. To get a power, for example, of
about two hundred times, the telescope requli
to be one Iiundi'ed and twenty feet in ]engtit.
Its other imperfections consisted, — J, in t1
rays of compounded light coming to their foci
difi'erent distances from the glass. Every ray of
light, as is found by the prism, is compounded
of various colors, and these have different foci,
the more refrangible, aa the violet, converging
sooner to ii point than those which are leaa re-
frangible, as the orange and the red. Hence the
image of an object formed by a single lens is in
some degree confused and tndisttacb,a,'ad.,^^'(A-
i
34
THE TELESCOPE.
fore, will not bear to have a high, powier pt
upon it. 2. Another imperfection was this, tin
spherical surfaces do not refract the rays of ligl
accurately to a point. The rays which pai
near the extremities of such a lens meet in fo^
more distant from the lens than those which pa%^
nearly through the centre, and hence are invar^^
ably colored.
To remedy these defects is the intention of the
achromatic telescope, the theory of which
first made known by Mr. DoUond, an optioi
of considerable celebrity in London. • The objeet-
glasses of this telescope are frequently composel
of three distinct lenses, two of which are convex .
and the other concave. The two which are cofr
Fig. 9.
vex are made of London crown>glass, and tb
middle one of white flint-glass, or that kind cf
glass of which wine-glasses and tumblers iii
made. Fig. 9 represents this compoimd triplB
object-glass, as it is fitted up in its coU, airi
V
placed H.I the object-end of the telescope.
it is now more frequently the practice with
IJoiane to form this object-glass double,
fig, 10, where * h is the conrex of urown glass,
1
Use ^*
i
And C » the concave of flint glass. The oonvei
is placed outside next the object, and the con-
care in the inside. By this combination of
passes, when accurately adjusted to each other,
an image of the object is formed without being
bimded with the piismatic colors. Hence the
word achromalic, by which this telescope is dis-
tinguished, signifies free of color. In conse-
quence of this property, such glasses will bear
B much larger aperture, and a much greater
magnifying power, than common refracting tele-
seo]}es. While a common telescope, whose
object-glass is three and a half feet focal dis-
tance, will scarcely bear an aperture of one inch,
the three and a half feet achroraalic telescope
will bear the aperture of three and a quarter
inches, and. consequently, will transmit more
tlUm ten times the quantity of light. White H
bear a magnifying power oC wiVj *^
36 THE TELESCOPE.
six times, the other will bear a magnifying
for astronomical purposes, of at least two ^^n^u
dred times ; so that a good achromatic iele^copi^
only four or five feet m length, will carry a
power equal to one of the common construction
one hundred feet long.
Manner in which achromatic telescopes an
fitted up for astronomical observations. — r, in fig.
11, is the body of the telescope mounted on a
tripod pedestal of brass, a is the eye-pieoe,
which screws off to admit other eye-pieces to be
applied, e is the long eye-piece for terrestrial
objects. D is an astronomical eye-piece, b con-
sists of two or three sliding tubes of brass, for
rendering the instrument steady ; and a is a brais
knob, which moves a piece of rack work for
adjusting the focus, a h the finder.
This telescope is now generally used. If
flint glass of a large diameter, and without
blemishes, could easily be procured, it woild
soon supersede almost all other telescopaft
But hitherto it has been very difficult, in Britaki»
to procure large discs of flint glass, of a good
quality, imless at a great expense. We have
been chiefly indebted for the largest discs of
flint glass, and for the best achromatic telescopv
we possess, to the French and Germans, wbft
charge high prices for such articM. But m
ic prospect, that glass for achromii-
aes may be procured Id greater abund-
at a more moderate cost, than Tormerly.
achromatic object-glnsa is prepared,
I in a tube, we apply magnifying pow-
in the same way as to the common
; only we can ti.>fV% \o '*. ft^e.-^»»»«»
8 THK TELESCOPK.
>f a much shorter focal distance — such
or quarter of an inch — than we can app]
object-glass with a single lens. But as i
piece for achromatic telescopes is difFere
that formerly described, it may be expedi<
to give a short description of it.
Section V. — Terrestrial eye-piece for ack
telescopes.
This eye-piece, which is represented in
consists of four lenses, combined on th
Fig. 12.
ciple of a compound microscope, a i;
ject lens, or that which Is next the ol
the amplifying lens, c the field-lens,
eye-lens, or that next the eye. At
formed near the glass a by the ol
From the image a second is formed ?
i, in the same position as the object.
at i might be formed by the lens a,
not be well-defined, owing to the gr
aberration, and therefore the lens i
a little distance beyond the focus
diaphragm, having a hole of a sr
,/
• THE TELESCOPE. 39
o A, at the focus of a, to cut oflf the colored
rays. The glass c is intended to enlarge the
field of view, and the image at i is viewed by
the eye-glass d. At the place where the second
image is formed, there should be a stop, m w,
to prevent any false light passing through to the
eye. As to the focal distance and arrangement
of these glasses, suppose the lens a one and
seven-eighth inches focal length, b may be two
and a half inches, c two inches, and d one and
a half; and their distances a b two and a half,
B c three and five-eighths, and c d two and three-
eighths. In a small pocket achromatic telescope,
whose object-glass was eight and a half inches
focal length, and its magnifying power fifteen
and a half, the focal lengths of the eye-glasses
were found to be, a 0.775 of an inch, b 1.025,
c 1.01, D 0.79 ; the distances, a b 1.18, b o
1.83, and c d 1.105.' This eye-piece would be
nearly equivalent, in magnifying power, to a sin-
gle lens of half an inch focal distance.
For the sai^e of those young persons who may
wish to construct an eye-piece of this kind, I
shall state the dimensions of one or two in the
possession of the writer. In one of these,
adapted to an achromatic object-glass five feet
three inches focal distance, and four inches dia-
meter, the lens a is three inches focal length,
40 THE TELESCOPE.
plano-convex; the plane side next the a
three and a quarter inches, c one and &^^
eighth inches, d one and a quarter inches. 'I^^^*
are all plano-convex, with the plane sides ^^^
the eye except the lens a. Their distances an^
A B three and three-fourths, b c five and three-
fourths, c D two inches. This eye-piece is eleven
and a half inches long, and produces a magni-
fying power for land objects of about ninety -six
times. The tube containing the two glasses next
the eye, c and d, being taken out, a tube con-
taining other two glasses is inserted, the focal
distances of which are, c two and a quarter
inches, d two inches, and their distance three
inches. This, in combination with the other
glasses, produces a power of about sixty limee^
If the glasses, c n, be placed in a movable tuhe»
c e^ a 6, by pulling out this tube, and conse-
quently increasing the disUince between b and d
the magnifying power may occasionally be in-
creased to one half, or nearly double what it had
in its original state. On this principle, Edich-
ener's Pancratic eye-tube is constructed.
Astronomical eye-pieces, — The combination of
lenses now most frequently used for astronomioii
observation is that which is denominated tUn
Huygenian eye-piece, which is a great improre-
ment on the eye-piece with, a &u\^le leua, aa it
cil of wliite liglit proceeding from the object-
glass, B p a pi uno- field-glass, with its plane side
next the eye-glass e. The red rays of the pencil,
A B, after refraetioD, would cross the axis in r
and the violet mys in v, but meetJag the eye-
glass E, the red ra}'s will be rei'racted to o, and
the violet nearly ia the same direction, when
tbey will cross each other about the point o in
the axis, and unite, so as to form an eye-piece
almost without uobr. Tlie distance of the two
glasses, f &, to produce tliis correction, must be
equal to half tiie sum of their focal distances.
Suppose the focal distance of the field-lens r to
be three inches, and that of k, the lens next the
eye, one inch, the two lensea should be placed
exactly at the distance of two inches ; in other,
words, the glass next the eye sliould be pla<
lis much wUhin the focwa ol ft\c ti^V^s^
iced
the^^l
42 THB TBLBSOOPE.
equal to its own focal distance. The focal lex^-o^
of a single lens that has the same i^SLgrn^yrnur
power as this compound eye-glass, is equal to half
the focal length of the field-glass. In the present
case, the focal length of a single lens which
would produce the same magnifying power
would be one and a half inches. The propor-
tion of the focal lengths of the two lenses to each
other should be as three to one ; that is, if the
field be one and a half inches, the eye-glass should
be half an inch. An astronomical eye-piece
may also be formed with two plano-convex
glasses, placed with their convex sides towards
each other, and at a very small distance from
each other, namely, somewhat less than the
focal distance of the lens next the eye. If, for
example, one of the lenses were one inch focal
length, and that next the eye three quarters of
an inch, they might be placed at somewhat less
than half an inch asunder.
Diagonal eye-pieces. — ^When a celestial object
is at a high altitude, the observer is obliged to
put his head in a very inconvenient position,
and to direct his eye nearly upwards, in which
position a steady view of the object can scarcely
be obtained. The diagonal eye-piece has been
invented to remedy this inconvenience. This
is eflfected by placing a flat piece of polished
THE TBLBSCOPE.
Fig. 14.
43
speculum metal, d c, fig. 14, at an angle of 45^
to the axis of the tube, a b. This part slides
into the tube of the telescope, e p ; the tube
containing the lenses stands at right angles to
the position of the telescope, and slides into an
exterior tube, a n, i o, and the eye is applied
at o. This construction of the diagonal eye-
piece may be used either with the Huygenian
eye-piece before described, or with that which
is formed of two plano-convex lenses, with their
convex sides towards each other. They may
be of any magnifying powers generally applied
to the. telescope, and may be changed at plea-
sure. The rays proceeding from the object-
glass and falling upon the plane speculum, d c,
are reflected in a perpendicular direction to the
eye-piece, e p, and enter the eye at g. When
this eye-piece is directed to celestial objects at
a high elevation, the observer may dtibec %»v\. <st
44 THB TELVBOOPE.
stand, and ]ook down upon the object with per-
fect ease. When it is directed to terrestrial
objects, the spectator likewise looks down upon
them, but they present a novel aspect, and
when the telescope is moved from one side to
another, they have the appearance of a moving
panorama. When the eye-piece is turned round
a quarter of a circle towards the right, those
objects which are in the south will appear as if
they were in the east ; when it is turned a quar-
ter of a circle towards the left, they will appear
as if they were in the west ; and when it is
turned half round from its first position, they
will appear as if they were above us, suspended
in the air.
A telescope furnished with a diagonal eye-
piece is the piost convenient for exhibiting the
spots in the sun. The window-shutters shoidd
be all closed, having a small opening sufficient
to admit the solar rajrs, and when the telescope
is properly adjusted, a large and beautiful image
of the sun, with all the spots which then happen
to diversify its surface, is thrown upon the ceiling
of the room, which must be of a white color
In this way we may measure with a scale the di
ameter of the solar image, and also the diametc
of a large spot, and by comparison we may dete:
mioe the exact diametrical proportion of the lattc
Seoiios VI. — Refiectiiig telescopes.
The great inconvenience attending tlie i
. BgPraent of the long refracting telescope
B smg!e object-glass, led to the invention of
reflecting telescopes. It is generally supposed
that Mr. James Gregory, son of the Rev. John
Gregory, minister of Dmmouk, Aberdeenshire,
■was the first who suggested the construction of
that kind of reflecting telescope which bears
his name ; but as he was eivAti^ni "frfla
M
46 TUB TELESCOPE.
mechanical dexterity, he never actually formed a
telescope according to his own theory. Several
years after he had published his description of
it, Sir Isaac Newton directed his attention to
this subject, and, in the year 1672, completed
two small reflecting telescopes, the construction
of which somewhat differed from the plan
Gregory had proposed in 1663. They were
only six inches long, but were considered as
equal in magnifying power to a common refract-
ing telescope six feet in length. Nothing more
was heard of reflecting telescopes till about half
a century afterwards, when, in the year 1723,
Mr. Hadley made a reflector on Newton's plan,
the large speculum of which was sixty -two and
five-eighths inches focal distance, and five inches
diameter, and was furnished with magnifying
powers of from one hundred and ninety to two
hundred and thirty times. It equaled in its
performance the telescope of Huygens, one hun-
dred and twenty-three feet in length. Reflecting
telescopes have been ever since in general use*
and have entirely superseded the long refractan.
We shall give a brief description of each of the
telescopes to which we have alluded.
1. The Newtonian reflector, — This instrument
is represented in fig. 16, where b a b f is the
tube, in which is placed the concave speculum
I
THE TELESCOPE. 4l
B B, which reflects the parallel rays o c, f d, to
a plane speculum q, which is placed at half a
right angle to the axis of the tube, as much
nearer the speculum than its focus as the centre
of the small mirror is distant from the tube ;
that is, the distance o A of the small speculum
from the focus of the great one should be equal
to o H, half the diameter of the tube. This
small speculum should be of an oval form, the
length of which should be to the breadth as
seven to five. It is supported by an arm fixed to
the side of the tube. The rays, o c,t d, which
Pig. 16.
B T ^^1 A
form the image of the object by reflection,
instead of proceeding to form it at h, are mter-
cepted by the plane speculum at o, and reflected
upwards to ^ aperture in the side of the tube
A B, where the image is formed, and magnified
by a convex lens of a short focal distance, to
which the eye is applied, looking dotonward on
the object, which appears inverted ; or, the eye-
glass, iostead of being on the upper part of the
tube, may be placed on one of the sides, and
for viewing land objectft a t«XT^\xssi\ ^^^^\<^<:^
r
may be applied. Tbe magnifyiiig power o/"
this telescope is in the proporlion of the fooal
distance of the speculum to that of the eye-glass,
Thus, if the focal length of the speculum be
axty inches, and that of the eye-glass a quarter
of an inch, the magnifying power will be two
hundred and forty limes. This is the form oC
the reflec^ng telescope which was moat gene-
rally used by the late Sir W. Herauhel, Tim
followmg table exhibits a statement of tixa dt
ameters of tbe specula of Ifewtoiuan I'efleoton^
the focal distances of their eye-glasses, und thetr
magnifying power: — -
L
FactH diaUmm
ApHrtnre
roCUl dlBlMM
MignlHrlnC
ofcvnare
Df
q>«»d.m.
eye^lsw.
In. Dec.
In. Deu.
1
1.44
0.9U prl
0.236 '
60
a
■W
102
3
HI
0.2(11
13S
4
1(1
0.281
171
6
W
0.287
203
a
iV/
0.311
233
7
L'+
0.323
260
8
RD
0.S34
asT
B
U
0.3*4
314
0.363
340
12
m
0.387
990
15
11
04
0.891
460
TBB 'ntLBSOOFB, 4h
It will generally be fouad, that the power pro-
duced by muliiplying the diameter of the specu-
lum by thirty or forty, is most satisfactory fu[ ■
planetary obserrations. J
2. Tlis Oregorwn rejlector. — This form of th»
reflecting telescope is constructed in the foUow-
uig manner : — ^i' t t i is tie great tube, open at
the end next the object, in which the lai'ge con-
care speculum d u v f is placed, whose principal
focus is at m, and in its middle is n round bole p,
opposite to which is placed the small mirror l,
concave towards Ihu great speculum, and so fixed
on a strong wire m, that it may be moved farther
from or nearer to the gi'etit miiTor. by means of
a, long screw on the outside of the tube. Tlie
rays proceedbg from the object a b, and falling
on the speculum d f, will be reflected to its focus
■m, where an inverted image of the object will
be formed.
This image is formed at a little more than ^ J
focal distance of the small speculum from its sitf" I
face, and the small mirror acting upon It, ttuftfl
first image is reflected through the glass r to a ^m
where a second image is formed erect, and lat;
than the first in the proportion of 6
This image is agwn magnified by the eye-glass s,
to which the eye is applied. The rays from the
glass s pass through the small hole « .'vVv^^on
Idom be more tlian one twenty-fifth of an incli
in diameter. To iind the magnifying power of
this telescope, multiply the focal distanee of the
great Epeculmn by t!ie distance of the small specu-
lum from tlie image nest tlie eye ; and multiply
the focal distance of the smalt speculum by tbe
focal distance of the eye-glass ; then divide the
product of the first multiplication by the product
of the last, and the quotient will be the magni-
fying power.
3. Oaisagrainian reflector. — This kind of re-
flector is constructed in the same wny as tbe
Gregorian, with this difference, that a small eon-
Vfx speculum is substituted in the room of the
Email concave l, fig. lY. This convex mirror is
placed as much leitkin tbe focus of the great
speculum as is equal to its own focal distancft
Thus, if the focal length of the large speoultsn
be twenty-four inches, and that of the small coo-
vex two and a half inches, they are placed >t
twenty-one and a half inches fiom each other,
and instead of two, there is ouly one image
formed, namely, that in the focus of the eye-glass,
The length of this telescope is leas than that of
a Gregorian by twice the focal length of the
small mirror. From the experiments of Short,
Ramsden, Captain Eater, and others, it appeu>
that there is more licrht in this t«le«coDe than h
THE TELESCOPE.
51
->
52 TIJE TELESCOPE.
O
the Gregorian ; and that it is, on the whole, sn
perior in its performance, but it represents ib
object in an inverted position.*
Short account of some large achromatic and n
fleeting telescopes,
1. Large achro7)iatic telescopes, — (1.) Tk
great Cambridge telescope, in Massctchusetts
United States, — ^This instrument was procurec
from Munich, in Germany, at a vast expense, anc
* Besides the telescopes described above, there an
plans of others by which distant objects may be viewed
1. A telescope may be made of a single lens of a lon|
focal distance. The writer has a lens twenty-six feel
focal distance and eleven and a half diameter, whicli,
without any other glass, produces a magnifying powei
of nearly thirty times, and by which he has read the
hour of the day on a public clock two miles distani
The observer stands at a distance of about twenty-fiTe
feet from the lens, his eye serving as the eye-glass,
on the principle of the Galilean telescope. 2. The
aerial telescope, constructed by the writer, which has
only one speculum, and in looking through which the
observer sits with his back to the object. This teles-
cope has no tube, but only a short socket to hold the
speculum. An arm at one side extends the length of
the focal distance of the speculum, at the end of whicb
is the eye-piece. 3. The Newtonian telescope may alsc
be fitted up toithotU a tubtj which saves considerate
expense. The writer has fitted up one on this plan,
which performs admirably. It may be changed at
pleasure into the aerial teVe^cope.
THE TELESCOPE. 53
it is considered as one of the best instruments of
the kind now in existence. The object-glass is
fifteen inches in diameter, and its focal length
twenty-three feet. It is placed on a block of
granite, thirteen tons in weight, adapted to an
equatorial apparatus, and clock-work is applied
to it, to give it a quiet sidereal motion. Almost
everything which has lately been discovered by
Lord Rosse has been seen through this telescope.
It has magnifying powers from two hundred and
fifty to above one thousand times. (2.) Sir J.
South*s telescope, — ^The object-glass of this tele-
scope, which was procured at Paris, is eleven and
two-tenths inches diameter, and nineteen inches
focal length. Thb telescope is erected on an
equatorial stand, at Sir J. South's observatory,
Kensington. (3.) The Northumberland telescopCy
in the observatory at Cambridge, is among the
largest of the kind in Great Britain. The object-
glass is said to be twenty-five feet focal distance,
and of a corresponding diameter. (4.) Paris Ob-
servatory . — In this observatory, when visited in
1837, there were two large achromatic telescopes,
which appeared to be jfrom fifteen to eighteen
feet long, and the object-glass from twelve to
fourteen inches diameter. (5.) The Dorpat teles-
cope, — ^This telescope was made by Fraunhefer
of Munich, for the observatory oi XW \\si^^^r^
54 TUE TELB8COPK.
Univereity of Dorpat, in the year 1825. Tbe
aperture of the object-glass is nine and a half
inches, and its focal length fourteen feet. lb
magnifying powers range from (me hundred and
seventy-five to seven hundred. It is moiinted on
an equatorial stand, with clock-work, and it ooat
£900. (6.) The Cincinnati telescope. — ^This tele-
scope was procured from Germany, and fitted
up by Professor Mitchell, of Cincinnati, United
States. It is mounted on equatorial machinery,
accompanied with clock-work. Its object-glass
is nearly eighteen inches focal length, and twelve
inches diameter, with magnifying powers from
one hundred to one thousand four hundred times.
The instrument with its machinery weighs about
two thousand five hundred pounds. (7.) 2ir,
Cooper' 8 telescope, — ^Mr. Cooper, M. P. for Sligo^
is in possession of a telescope, twenty-six fe^
long and the diameter of the object-glass is four-
teen inches. (8.) Dr, Pearson's telescope. — This
gentleman, who is secretary to the Astronomical
Society, is in possession of a telescope made by
the late Mr. Tulley, the object-glass of which is
twelve feet focal length, and seven inches diameter.
(9.) Mr, LawsorCs telescope, — ^This gentlemaOi
who is a diligent astronomical observer, possesses
a most beautiful telescope, twelve feet focal
length, and seven inches diameter, made by one
of the DoUoudB. It is said to bear poirerB of
one thousand ane hundred or one thousand two
hundred. (10-) Mi: SridrKs's telescope. — This
\ gentleman has fitted up at Blackheath a. telescope
I on equatoiiul machinety, whose object-glasa is
I live and a. half feet focal Eength, and five and a
I half inches diameter. The object-glass cost two
hundred guineas, the equatorial machinery one
" hundred and fifty, and the obsorvatory one hun-
dred guineas ; in all, four hundred and fifty gui-
" neas. (11.) Captain Sniilh'« telescope, at Bed-
I ford. — This instrument is eight and a half feet
I fo<ml leagtli, and sh inches diameter, and will
bear a maguifying power of one thousand two
liundred.
2. Larye mjlectini/ lelfKopea. — Mr. Jaraes
' Short, of Edinburgh, was the first who made
I reflecting telescopes on a large scale. In 1743,
he constructed one for Lord Spencer, of twelve
' feet focal length, for which he received six hun-
dred guineas; and, in 1752, bo finished a still
larger one for the King of Spain, for which he
received one thousand two hundred pounds
Bterling, This was considered the noblest in-
Btrument of its kind till Herschel constructed
his large reflectors. About the year IVSO, the
late Sir W. Ilerschel constructed a Newtoniaji |
. reflector, twenty feet long, with which he «
56 THJB TBLS8G0PE.
1
plored the Milky Way, and other objects in the
sidereal heavens. In 1789, he finished his large
forty-feet telescope, which at that time was un-
rivaled. Its speculum was four feet diameter,
and it had neither a concave nor plane small
spectdum, but the observer sat with his back to
the object, and looked down upon the great
speculum. This telescope was dismantled a few
years ago. A large telescope, twenty feet in
length, has lately been constructed by Mr. Lar-
sels, of Liverpool, with which he has discovered
several small planets. But the largest reflectorB
now in existence are those which have been
lately erected by the Earl of Rosse. One of I
these, in the lawn before his lordship's mansion^
is twenty-seven feet long, and its speculum three
feet diameter. Another, called the ''monster
telescope," is fifty-six feet long, and its speculnm
six feet in diameter, and weighs above three
tons. This is the largest telescope in the world,
and its erection cost his lordship twelve thou-
sand pounds sterling. It is of the Newtonian
form.
Prices of telescopes, of a moderate size, as made
by the London opticians, — ^To such of our readers
as may be desirous of puirsuing astronomical
studies, the following list may be useful.
The instruments specified in the preceding
TBB TBUUOOPK. &7
pages are only made lo order, nnd are, conse-
qoently, very expensive. The more common
sjzea of telescopes for astronomical purposes are
the following ; —
1. Achromatic lelescopes. — '' The improved
tno and a half feet achromatic, on a brass stand,
msliogaoy tube, with three eye-pieces, two mag-
nifying about forty or fifty Umes, and the other
about seventy-five for asLrooomical purposes, in
malu^^any case, illO 10s. ; ditto, with brass tube,
illl lis.; ditto, vith vertical and horizontal
rackwork motions, £I5 15«." This telescope,
if the objeot-glasa be good, will bear a power
of ninety or one hundred times for oeleatial ob-
jects. Its ohjecL-gluas is two and a quarter
inches diameter. " The three and ii half feet
uchromalic, plain mahogany tube, two and three-
qujirters aperture, £18 ie». ; ditto, brass tube,
• £21 ; ditto, all in brass, with nickwork motions,
£26 &j. ; ditto, the object-glass of throe and a
quarter inches aperture, and having improved
rackwork motions, from £37 Ifls, to £42." The
magnifying powers of these telescopes are from one
hundred and thirty to one hundred and eighty or
two hundred times. Tliis is the telescope whiA.
we would recommend to iistrouomical observeiK.]
It will show all the common phenomena o
solar system, Tho fire ftti tttitTomi).ti.t '\
58 THE TELtSOOl'E.
frequently made: diameter of the object-giB»
three aad eight-tenths inches ; powers, sixty-fiv6i
one hundred and ten, one hundred and ninety,
and two hundred and fifty. Its general price is
above one hundred guineas. Achromatic object-
glasses for such teSescopes may sometimes be
purcliased separately, at such prices as the fol-
lowing ; — Focal length, thirty inches, diameter
two and a quarter inches, from two to two and
a haJf guineas ; focus forty-two inches, diameter
two and three-quarter inches, from five to eight
guineas ; focal length forty-two inches, tUameter
three and a quai-Ler inches, from twelve to twenty
guineas. Eye- pieces may be procured from 10».
erf. to 14)1.
2, Rejieclini/ telescopes. — The reflectors oom-
mouly made and sold in London are the follow-
ing:—
A four feet seven inch aperture, Gregorian-
reflector, with the vertical motions upon a new
principle, with apparatus to render the tube
more steady for observation, according to the
additional apparatus of small specula, eye-piecea,
micrometers, etc., from £S0 to £120: three feet
long, mounted on a brass stand, £23 3s. ; ditto,
with rackwork motions, improved mountings aad
metals, £30 16«. ; two feet long, without rack-
Work, and with four magnifying powers, Xld
!ce tt/^^M
16s.; ditto, improved, irith raokwork motioi^
£22 1«, ; eighteen inch, on a. plain stand, £0 9s, ;
twelve inch ditto, £8 6j.
Sectios TII, — Discoveries which have been
bi/ meam of ike telescope.
The human eye is a most wonderful piece
mechanism; it is a natural telescope, nearly
spherical in its form, and exquisitely delicate
and beautiful in its struoturc. The complete-
ness of its organization, and the perfect ease
and rapidity with which it fulfills all its functions,
show that He by whom it was " formed " de-
signed it to minister continually to our instruc-
tion and happiness. We need not endeavor to
imagine what would have been our helpless and
hopeless state oL uncertMnty, confusion and dis-
tress, had we been without tho faculty of sight.
Almighty wisdom and benevolence could not
f(ul to render our existence harmonious, to adapt
our perceptions to our condition, and to endow
us with those senses which are necessary to a
wise and satisfactory enjoyment of life. " Of
all our senses," says Mr, Addison, "our sight is
tlie most perfect and delightful ; it fills the mind
with the largest variety of ideas, converses with
its objects at iho greatest distance, and coatini
the longest, in action without b«,\'C;^ ^n«t&.
60 TBS T1UB9COPX.
satiated with its proper enjoyments." Abon
all is it Tallied by those who, in the oo namloi
ness of their relati(»i to God as bd&even k
Christ, rejoice to commune with hinoi m the
works of creation. '*The endless Tolttme of
nature, full of beauty, and illuminated by Hea-
ven, seems to them sufficient to fill the soul with
satisfaction forever, because here they leam k^
miliarity with the attributes of a Power Hmj
may trust as thoroughly as they can admiiB.***^
But our vision, at the best, is feeble, and H ii
limited within a very narrow range. From Iks
brow of a hill we may look on an ex tcu M Ue
landscape, but it is only within two or tkne
miles that its varied beauties are distinctly seea
Even at this distance we cannot distingiiish a
friend, or read a sign, or accurately desoribeHiB
actions of our fellow-men. If we gaze up into
the sky on a dear evening, we see the. moon, it
may be a slender crescent, or a full enlightened
orb, or one of the vfflied phases between ihittlte
two extremes ; we see five or six hundred glelnift-
ing sparkles of light, which we call stars,
we see a lustrous cloud eneompasring a
siderable part of the heavens : but here the dk-
coveries of unassisted vision terminate. 8oiift
o The Influence of the Body in relation to the MbtiK
Bjr George MooKt M.D.
.^^
THE TELESCOPE. 61
more intelligent and scrutinizing inquirer may,
indeed, detect differences which others overlook,
and perceive order where they only find confu-
sion; and these observations may suggest to
him truer and sublimer conceptions of the uni-
verse than the unassisted organs of vision can
give. But he can be satisfied with nothing less
than cei-tainty, and he is bewildered and op-
pressed by doubt and mystery. To him how
valuable are the discoveries of the telescope,
and how important are they to all, for the stu-
pendous proofs which they afford of the omnipo-
tence of the Creator, and of the vastness of his
dominions !
We shall now give a brief sketch of these dis-
coveries, both within the solar system and in the
sidereal heavens.
Discoveries in the solar system.
The moan, — The nearest to the earth of the
heavenly bodies is the moon. By the telescope
it has been discovered that a very large number
of mountains diversify its surface. They are
from half a mile to ^yq miles in perpendicular
elevation, and are almost universally rounded in
their form. They may be classed in the follow-
ing order: — 1. liisulaied mountains which rise
from plains nearly level, like Ok ^^Oii^Asi^ ^^Ri^^
62 THE TELESCOPE.
table. 2. Ranges of mountains, extending in
length three or four hundred miles, resembling
our Alps and Apennines. 3. Circular ranges,
surroimding either a cavity or an extensive plain,
from which rises centmlly a mountain of con-
siderable height. There are also caverns in the
moon, some of which are more than two miles
in perpendicular depth. Their diameter varies
from three to forty or fifty miles, and the larger
ones have flat bottoms. Nearly a hundred of
these caverns may be seen on the south-western
part of the planet. Although there are large
regions in the moon perfectly level, and which
seem to be of an alluvial character, no seas or
large collections of waters can be discerned in
it, and in its atmosphere there is no appear-
ance of clouds. It has been ascertained that
the moon always turns the same side to the
earth, so that we see nothing of the other hemis-
phere.
The Sun, — Among the first discoveries of the
telescope was the motion of certain dark spots
across the disc of the sun. T^ey have since
been more closely observed, and by them it has
been calculated that the sun revolves on its axis
in twenty-five days and ten hours. These spots
are of various sizes, from one twentieth of the
8UD*8 diameter to one five hutvdxedtVv oxvii \v\der.
1
■IHE
Tliey have a dai-k centre, surrounded hy a bor-
der of fainter shade, called an umbra. Some-
times the sBme umbra includes one or two large
spots and a, number of very small <
other times the latter accompany the former H
n kind of train. Occasionally the s
i\lraoat free from spots, but often nearly a hnw 1
dred may be seen on its surface at one time.
The sun ia supposed to lie a solid globe, sur-
rounded by a luminous atmosphere, from whence _
heat and ligW are diffused through the p!aM
tary system, it is probfthle the f
opnque hody seen through that atmosphei'
■when any portions of it B.re more rare or thinni
tban usual.
Vemis and Mercary. — Venus is the brightd
of the planets, and is known as the morning a'
the evenbg star : it is the morning star when it
is west of the sun. and rbes before it; and the
eTemng star when it is east of the sun, and setfr^g
after it, One of the earliest discoveries of t
telescope was the fact that Yenus passes thro
the Barac phases as the moon, appearing, ;
its inferior conjunction with the sun, and when
its dark side ia turned towards the earth, first
as a crescent, then as a half moon, then gibbous,
and at length a.s a full enlightened hemispher^j
This discovery was an impottiiiA ccfl&TvwS.vaa."?r
large
indat^^
nertt^H
•peari^H
, sur-
hence
hen it
d the
md setfr'^^_
throu^fl^^H
g, afta^H
tlie theory of Copernicus, tliat this planet did
not move round the earth, as was formeHj
supposed, but round tlie sun, and in an ortit
between the earth and the sun. It proved, also,
that the planete are dark bodies, and derive flU
their light from the centi'al luminary. From
subsequent elimination it was found that yenns
turns round its axis in twentj-thrce hours and
twenty-one minutes. With the telescope it baa
been observed on different occasions to transit
the sun's disc, by which the distance of the sun
has been more accurately detennined. Pew
discoveries have been made in Mercury, on ac-
count of its nearness to the sun. It has been
found, however, that it passes through all tbo
phases of the moon, in the same way as Venus;
tliat it moves round its axis in twenty-four hotm
and three minutes ; and that high elevations pro-
ject from its surface.
Mam. — ^This planet is remarkable for its
color, which is a glowing red. Sometimes it
looks nearly as lai^ as Jupiter, and at other
times it appears as if it had dwmdied lo the Nze
of a small star. These variations are owing U>
its different distances from the earth, the two
extremes of which are fifty, and two hundred
and forty millions of miles. It moves in an orbit
e distant from the sun than that of the earth.
and accomplishes its revolution In one yeav and
ten months. Spots have been diecove/^ed on ils
aurfuce, whicii seem to indicate the existence of
land and water. A wliit<i spot has likewise
been discovered near its south pole, which is
supposed by some to ariee from the reflection
of the sun's light around the polar region^
The red hue of Mars is occasioned by the dei
atmoephere with which ]t is surrounded.
watching its spots it has been found to have
rotation round its axis in twenty-four hours and
thirty-seven minutes. This planet is of a Bphe-
rcudal figure, like the earth, having its polar
diameter two hundred and sixty-three miles
shorter than its equatorial, which is four thou-
sand two hundi-ed miles. From these and
other obsen-Jitions, it has been concluded that
about one-third or one-fourth of its surface is
covered with water, that there ate strata of
clouds of con^derable extent occasionally float-
ing in its atmosphere, and that it has
of seasons similar lo our own.
TTie nrai planets between the orbits of
and Jupiter, — Within the Umilti of the present
century, certain comparatively small anomalous
bodies have been discovered, revolving around
the sun in the re^ons between the orbits
Uars and Jupiter, The great dlatance
1
in«i^J
ea"^
' float-
^hangg^J
66 THE TKLEBCOFE.
inteirenes between Mars and Jupiter led astro-
nomers to suppose that a planet existed some-
where witbih that part of the planetary system.
But they were astonished when it was fonnd
that not only one planet, but a considerable
number, were running their courses m that
region. The first of these planets was discover-
ed on January 1st, 1801, by Piazzi, at Palermo,
which is named Ceres; the second, named •Tuno,
by Professor Harding of Gottingen, in 1804;
the third and fourth, named Pallas and Vesta,
in 1802 and 1807, by Dr. Olbers of Bremen.
No further discoveries were made till December
8th, 1845, when Professor Hencke of Driessen
discovered Astroea ; and on the 6th July, 1847,
the same gentleman discovered the planet JSSpftf.
Mr. Hind, at the Observatory, Regent's Fait,
London, August 18th, 1847, discovered Iris, and
on the 18th of October, the planet Flora, On
April 25th, 1848, Mr Graham discovered Metis,
On the 12th April, 1849, M. De Gasparis, of
the Observatory at Naples, discovered Hygeia;
and on the 11th May, 1850, another, which he
calls Parthenope. On September 13thy 1850,
Mr. Hind discovered another planet in the con-
stellation Pegasus, which appeared like a star of
the ninth magnitude, and with a pale bluish
Ji^ht; he intends to call it Victoria, This fomns
THE TELESCOPE. 67
the twelfth of the group of the new planets, of
which eight have been discovered within the
space of little more than four and a half years.
All these planets are invisible to the naked eye,
and<2onsequently their existence would never have
been known without the telescope. Their mag-
nitudes are not yet accurately decided. Shroeter,
a celebrated Oerman astronomer, calculated the
diameter of Vesta at two hundred and seventy-
six miles, of Juno at fourteen hundred and twenty-
five miles, of Ceres at sixteen hundred and twenty-
four miles, and of Pallas at about two thousand
miles. There is a considerable degree of mys-
tery connected with these planets, which it is
not easy to unravel. Their orbits have a much
greater degree of inclination to the ecliptic than
those ci the other planets ; they are more ec-
centric, and several of them cross each other ;
they revolve nearly at the same distances from
the sun, they perform their revolutions nearly in
the same periods, and they are all much smaller
than those previously discovered. It has been
thought, therefore, by some, that these planets
are the fragments of a greater planet, which had
fcnrmerly circulated between Mars and Jupiter,
and which an hnmense irruptive force from its
interior had burst asunder. This, however, is
mere speculation.
f
/
68 THE TELB800FK.
Jupiter, — This is the largest planet in i
solar system. It is eighty-eight thousand mi
in diameter, and in bulk exceeds that of t
earth about thirteen hundred times. Dark beL
which frequently shift their position, and vf
in breadth as well as in situation, embrace
whole circumference. These belts are, probab
it« real surface, and the intervals between tb
some astronomers suppose to be the clouds in
atmosphere. Large spots have been seen
Jupiter, and by these it has been shown that
revolves round its axis in nine hours and fift
six minutes. It is attended by four moons,
satelUtes, which, it will be remembered,. w(
among the first discoveries made by Galileo wi
the telescope. These satellites are seen indiffi
ent positions. Sometimes two are seen on o
side of their primary, and two on the other sid
and sometimes all four are seen in their regul
distances on one side, nearly in a straight li
from each other and from the centre of i
planet. At other times, only two are visib.
the other two being eclipsed by the shadow i
Jupiter. The first satellite, or that nearest tl
planet, revolves round it in forty-two hours ai
a half, and suffers an eclipse eighteen times
every month. The eclipses of these satellit
are of considerable use in determining the lon^
THE TELESCOPE. 69
tude of places on tbe earth. Jupiter, with his
moons, which are all invisible to the naked eye,
is a most splendid object when seen through a
powerful telescope, and presents a field for con-
templation which never fails to astonish and
delight by its magnificence and variety.
Saturn, — The planet Saturn is nine hundred
and six millions of miles from the sun, which
is nearly double the distance of Jupiter. It is
seventy-nine thousand miles in diameter, and
nearly a thousand times larger than the earth.
It has dght satellites. Some dusky spots have
been occasionally seen on its surface, by the
motion of which its diiunal rotation has been
found to be accomplished in ten hours and six-
teen minutes. Belts have likewise been discov-
ered in Saturn, almost resembling those of Jupiter,
but fainter, and invariable in their position.
The belts of Saturn also cover a larger zone on
the disc of the planet. But the most remark-
able discovery which the telescope has made in
connection with Saturn is, that, at a distance from
it of more than twenty thousand miles, it is sur-
rounded by an immense double ring. This ring,
or rather these rings, are concentric with the
planet and with one another, both lying in
one plane, and separated from each other by an
interval of more than two tho^isoxvixfiaiSL^^. ^^^^
3 TUB TELESCOPE.
'Utside diameter of the exterior ring exceeds two
lundred thousand miles, its circumference is up-
wards of six hundred and thirty thousand miles,
and its breadth is seven thousand two hundred
miles. The outside diameter of the interior ring
is one hundred and eighty-four thousand miles,
and its breadth twenty thousand miles. These
rings, reckoning the extent of surface on both
sides, contain an area of more than twenty-eight
thousand eight hundred millions of square miles ;
that is, it is equal to one hundred and forty-sax
times the number of square miles on our own
terraqueous globe. The rings revolve round the
planet every ten hours and a half, which is at
the rate of more than a thousand miles every
minute. They preserve an invariable distance
from the planet at all times, and along with it
are carried round the sun in the space of twenty-
nine years and a half. If viewed from the planet
itself, they would appear like magnificent lumi-
nous arches, stretching from east to west across
the heavens, and difiPusing at night a mild radi
ance. From our distant point of observatioi
we may learn by these stupendous phenomei
that Omnipotence is everywhere present, a'
that He who regulates and keeps in perfect h
mony the movements of all worlds, must be
in£mte m goodness as he k in ^ower.
THB TELESCOPE. 7l
Uranus. — ^This planet is 1,800,000,000 of
miles from the sun, and about 900,000,000 of
miles beyond the orbit of Saturn. It remained
invisible till the year lYSl, when the telescope
revealed it to Sir. W. Herschel. It revolves
round the sun in an orbit 11,314,000,000 of
miles in circimiference, in the course of about
dighty-four years, at the rate of fifteen thousand
miles an hour. Owing to its great distance from
uSy. no spots or belts are discernible on its sur-
face, and consequently the period of its diurnal
rotation is unknown. Its magnitude is estimated
at thirty-five thousand miles in diameter, or
about dghty-two times larger than the earth.
It has four satellites, and probably five or six ;
but their periods are not ascertained with ac-
curacy, and their orbits present remarkable
peculiarities.
NeptwM. — ^This planet was discovered on the
28d of September, 1846, by Dr. Galle, of the
Royal Observatory at Berlin. Its place had
been calculated, even before it was discovered,
by Mr. Adams of Cambridge, and M. Leverrier
of Paris, by whom its position in the heavens
was pointed out within a degree of the spot
where it was actually found. It is probably the
planet whose existence and position had been
also calculated by Professor Challis of the Ob-
72 THE TELESCOPE.
servatory of Cambridge, on the 4tli and the 12tik
of August, 1846, but he declined publishing fail
observations at that time. Neptune appears Hke
a star of the eighth magnitude ; its distance
from the sun is about thirty times that of the
earth, or more than 1,000,000,000 of nules be-
yond the orbit of Uranus. Its diameter is fifty
thousand miles ; it is therefore two hundred and
fifty times larger than the earth, and its revolu-
tion round the sun is accomplished in one hun-
dred and sixty-four years. Mr. Larsels of
Liverpool, from several observations has con-
cluded that it is surrounded hy a ring, and Pro-
fessor Challis and others have formed the same
conclusion. Mr. Larsels has also ascertuned
that it has two satellites, one of which revolves
round it in five days twenty hours and fifty
minutes.
Discoveries made hy the telescope in the sidereal
heavens.
Of late years the telescope has been more
particularly directed to the starry heavens than
in former times, and many wonderful discoveries
have been made, of which it is impossible to give
more than a meagre outline.
1. The distance and magnitude of the fixed
stars, — ^The determination of the distance of 8
ttar depends on the angle of paralkjt formed by
viewing it from opposite parts of the earth's
Jttbit, which ^ves a base line of 190,000,000 of
niles in eitent. But the angle formed by thia
fine at the stars is so small, that astronomers '
jfaave had great difficulties to encounter in order I
io adjust it. Of late, however, this point has
Jbeeti settled in reference to some of the fixed
Mbtb. Professor Bessel, some years ago, deter-
painedthe angle of parallax of the star sixty-one
Ct/ffni to be somewhat more than one-third of a .
)|scond, 'which makes the distance of that star to 1
^ above aixti/ billions four hundred thousand 1
pKilliora of miles, a distance through which light, J
^yiDg at a rate of one hundred and ninety-two 1
Ihousand miles every moment, would require tou' I
ifears to pass. Another star, a Cenlouri, has ■
JtliA its parallax determined to be the ten- 1
jtlevenths of a second, which mokes the distance 1
||Ah>70 twenlij billions of miles. And as the ]
bttSgnitude of a. st«r depends upon our knowing j
pta distance, the magnitude of these stars must J
•be mncl) larger than that of our sun. J
j The Milky Wny.^'Ous is an irregular white ]
^ono, which, with some variations, eocompassea J
,tite heavens in a great circle, inclbed at an ■
:lBgle of 03° to the eqiunoctial. The telescope 1
AaB enabled us to ascertain thtri. l\i« -«\iAjn«aft 1
1
74 THE TELESCOPE.
of this zone is owing to the countless multitude
of stars which it contains. In a powerful ghm,
the field of view will be filled with more than a
hundred stars; and turning the instrument to
the right and left, or up and down for a con-
siderable distance, a similar niunber will appear
with every change of its position. So crowded
are the stars in some parts of this zone, that Sir
W. Herschel, by counting the number in a single
field of his telescope, concluded that fifty thou-
sand had passed under his review during an
hour's observation. It has been calculated that
in the Milky Way there cannot be less than
twenty tiiillions of stars, which is twenty thou-
sand times the number of those visible to the
unassisted eye. And if every star be a splmidid
sun, surrounded with planets, as we have every
reason to believe, how overpowering is the sense
of indefiniteness as to the extent of the universe I
And yet when we see ** confused clouds of gloiy
revolving themselves into systems of orderly
worlds," we rejoice in the thought, that He who
made them ** telleth the number of the stars ;
he calleth them all by their names," Psa. cxlvH, 4;
and that with him order and arrangement indi-
cate a ceaseless and beneficent superintendenoe
of all '* the works of his hands."
Double 8tar8.-^T\ie;re axe numbers of stan in
THE TELESCOPE. 75
the heavens, which appear single to the naked
eye, but when viewed through a telescope are
discovered to be double, and sometimes triple, or
quadruple. These double stars are generally of
different magnitudes ; and it has been frequently
found, after a long series of observations, that
the smaller star performs a revolution around
the larger one. Above fifty instances have
been ascertained in which one star revolves
round another; and although insome of -these a
complete revolution has not yet been witnessed,
yet from what has been observed, the period of
entire rotation has been determined. One of
these stars, ri Coronse, accomplishes its revolu-
tion in forty-three years ; another, a Leonis,
in eighty-two years ; and another, a Castor, in
two hundred and fifty-two years. Here we have
the astonishing spectacle of suns revolving around
BunSy and systems around systems! Another
interesting fact is, that these stars frequently
exhibit contrasted colors : the large star is usually
of an orange hue, while the smaller one appears
Uue or green ; in other cases, the large one is a
white star, and the smaller one a rich ruddy
purple. What a dissimilar illummation must these
suns afford, yet how beautifully do their colors
harmonize ! The works of God are as perfect as
they are inexhaustible in wonders QiSid\TiNm<^\?j .
78 THE TELESCOPE.
not more than a tenth part of that covered hf
the moon." More than three thousand nebuls
have been discovered in different parts of the
heavens ; and if they are all resolvable into as
many stars as this calculation supposes, it wOl
add fifteen millions to the number before be-
lieved to exist. But some of the distant nebulse
are thought to equal the Milky Way in the
number of stars; for if that galaxy had been
placed at such a remote distance from ns as
some of the nebulee, it would have appeared
no larger than these now do, when beheld as
dim specks even through the telescope. The
planetary nehulcB are a very extraordinary ckss
of objects ; they have a near resemblance to
planets, presenting discs round or slightly ovaL
One of these is situated somewhat south of the
parallel of j3 Wrsce Majoris, and about 12' follow-
ing that star. Its apparent diameter is 2^ 40" ;
and " supposing it placed," says Sir J. Herachd,
'* at a distance no greater than that of sizty-<Hie
Cygni, would imply a linear diameter seven
times greater than that of the orbit of Neptune."
Now, a body seven times the diameter of the
orbit of Neptune would be nearly twenty thou-
sand millions of miles in diameter. Of such a
body we can have no adequate conception. We
are overwhelmed by its magnitude, and can
11
The cause of their variation is unknown, thougii,
ia Bome instances, there can be little doubt that
it is occaaioued by the interposition of opaque
bodies, snch as the planets,
Clwters of stars and the Nebulis. — When
we look up to the heavens in a clear evenmg,
we perceive groups of stars compressed within
narrower limits than other constellations. Then
is a remarkable chieter, called the Pleiades, ia-
which a common telescope shows about sixlf
largo stars crowded together. There is anothOTi.
scarcely visible to the naked eye, in the con*
Btellittioa Cancer, called Prasept, which contain*
about forty or lifty brilUanl stars ; and in thd
Bword handle of Perseus there is a most beau-
tiful group, which can only be seen with a tele-
scope. They are called clusters, and are sup-
posed lo be drawn together by the influence of
cert^n physical laws. Jf^ebulw is the name
given to small cloudy spots which are seen in
the heavens. Many of these nebulse are found
to be thick set with stars, which powerful tele-
scopes alone enable ua to distinguish. They
are not to he reckoned by hundreds, but hf
thousands. "On a rough calculation," saya.
Sir 3. Herschel. " it would appear that maay
clusters of this description must contain at least:
five thousand stars, compacted in a round sftaot
1
I
80 THE TELBSCOPS.
Beflections suggested hy the discoveries of (A
telescope.
1. How impressively do the discoyeries of th
telescope illustrate the ahnighty power of God
Let the reader reflect for a moment upon th
view which this admirable instrument presenl
of the extent of creation. There was a tinM
when the conception of neither poet, philosophe
nor divine, soared beyond the sphere of iinaide
human vision ; and when, looking upon the eart
as the lai'gest body in the universe, and tl
sim, moon, and stars as mere appendages 1
enlighten and adorn it, they imagined all tli
Creator's works to be confined within thee
narVow bounds. But the telescope ha& opene
to us a field to which no limits can be assignei
Within our own planetary system it has dii
covered to us bodies more than a thousan
times larger than the globe we inhabit ; and i
the distant starry regions, beyond our nean
circle, it has shown to us myriads oi sun
equal in magnitude to the one which rules oi
day, and each the centre of other worlds* a
of which are probably teeming with happ
dwellers. Nor is this all; for as one bi^
scene of splendor rises above another, in alma
boundless perspective, who can doubt that other
THE TELESCOPE. Si"
yet more wonderful and Bublime, lie beyond the
range of the most powerful telescope? ^
it lias taken us to the farthest line of ohs
tion it can reach, who will say that " the
iere of the Almighty are at an end, because ne
fflR no longer trace his footeteps ? — that his
iupotence is ezliausted, because human heart'
can no longer follow him ?"
Scarcely less calodsted to raise onr concept
lionB of the almighty power of God, is the maff-
Hilitde of the objects whiclk the telescope brings
under our notice. The planet Jupitci
puted to be more than thirteen hundred limes
larger than the earth. The sun is five hundred
times larger than all the planets and comets
would be, were it passible to unite them
TBst globe. The star a Lyric is reckoned to be
three million two hundred and sevenly-five thi
sand mile* m diameter, and more than fifty-four
thousand times larger than the sun. Omnipo-
tence is impUed in the existence of an atom as
well as of a world, but we realize that atlribut*'
mora vividly in the latter than b the former.
We look at our own globe, with all its mighty
oceans and contment«, conttuaing more than two
hundred and sixty thousand millions of cubical
miles of solid matter, and -we are astonished at
the power of the Creator ; but bow ^ tiiSS.
G
I
i
L
88 * THE TEtBBCOPE,
tonisbment increased, when ve leam from the
discoveries of the telescope, that, instead of be-
ing disHnguislied from otiier worlds, it ia one of
the least of them — a mere atom in creation ; and
(hat in coinparison nith other systems, the ons
in which this atom is fomtd is but a mere shred,
which, though scattered into nothing, wDnM
leave the universe of God one entire soeno d
greatness and of majesty 1
To these considei-ations may be added the
veloetty with which these stupendous bodies more
in their courses. The planet Saturn, with Its
rings and moons, moves in its circuit round the
stm at the rate of twenty-two thousand roilee an
hour, The planet Venus performs its revoliition
ttt the rat* of eighty thousand miles an hour,
and the planet Mercury flies through its orUt at
the extraordinaiy speed of one hundred and nine
thousand miles an hour. The motion of some
of the fixed stars, a million times larger than the
em-th, has been calculated to he one hundred
and seventy thousand miles nn hour, and the
velocity of some of the comets is known to be
no less than eight hundred thousand miles an
hour, or more than thirteen thousand miles p
minute. When we reflect, too. on tlie size am
number of the heavenly bodies, on the proba
lii/U}' that they all move with a tftplM'j ■«
THE TELESCOPE. * 83
if it be not impossible to calculate, is most diffi-
cult to conceive, and that there is an order and
harmony in their motions which prove them to
be controlled and regulated by a will as omnipo-
tent as that which called them into existence, we
cannot refrain from exclaiming with the psalmist,
when he thought upon the glories of the firma-
ment, " Great is our Lord, and of great power."
Psa. cxlvii, 5.
2. How striking and beautiful is the coinci-
dence between these discoveries of the telescope
and the representations of Scnpture ! It is im-
possible to determine whether the wonders which
modem astronomy has brought to light were re-
vealed to the sacred writers. But how remark-
ably consistent is their language with all the
wonders which the telescope has revealed !
Where would the devout astronomer, laying
down the instrument with which he has explored
the heavens, find the most suitable expression
for those feelings which have been awakened by
what he has there seen of the glory and power
of the eternal Creator ? Where would he find
language more elevated and appropriate than in
the sacred volume? And in this concurrence
between science and Scripture, have we not an
additional confirmation of the fact, that the God
of nature is the God of the Bible ?
84 THE TELESCOPE.
3. All subjects, as they are exhibited i
Bible, have reference to the great work <
demption. The cross of Christ is a centre
whence the Christian will survey the uni
The hill of Calvary will be his observatory
how unutterable will be the emotions with
he will " consider " the heavens, when he re
bers that their almighty Maker is his Rede<
"All things were made by him; and wi
him was not anything made that was m
John i, 3. There is a rapture felt in gazv
the starry sky, which can be only known t
in whose heart the Saviour is enthroned.
will see all the glories of creation reflect!
the mediatorial work of that Saviour, and
discovery which expands his views of the f<
will exalt his conceptions of the latter. " [
worlds of light," he will say, " those cou
suns and systems which the telescope I
within my sight, and in the contemplatic
which, either individually or collectively,
lost in astonishment and filled with awe, a
the workmanship of my Redeemer. And
so ? Then how transcendant must be his g
Do I go to Bethlehem, the place of his inc
tion, and see him,
* On whom the vast universe hung,'
THE TELESCOPE. 85
as an infant cradled in a manger? What an
infinite depth of condescension ! Do I visit the
place of his crucifixion, and see him bearing
' our sins in his own body on the tree V 1 Pet.
ii, 24. How inestimable mu§t be the value of
the sacrifice ! Does my faith follow him from
the scene of his abasement to that of his exalta-
tion? Do I behold him as Mediator, invested
with absolute and unlimited sovereignty ? How
is my confidence strengthened ! Surely * he is
able also to save them to the uttermost that
come unto God by him.* Heb. vii, 25." .
Nor let it be imagined that the magnitude of
cregtion affords any reasonable objection to the
scheme of redemption as revealed in the Bible.
The objection has been made ; but its whole force
is met in the one simple consideration, "that
God, in addition to the bare faculty of dwelling
on a multiplicity of objeOT at one and the same
time, has this faculty in such wonderful perfec-
tion, that he can attend as fully, and provide as
richly, and manifest all his attributes as illus-
triously on every one of these objects, as if the
rest had no existence, and no place whatever in
his government or in his thoughts."* And in
^ " Discourses on the Christian Revelation, viewed
in connection with modem Astronomy," by Rev. Dr.
Chalmers.
86 THE TELESCOPE.
illustration and proof of this position, let it be
remembered that soon after the invention of the
telescope, which put infidelity in possession of
the objection, another instrument was found,
** which laid open a scene no less wonderful, and
rewarded the inquisitive spirit of man with a dis-
covery which serves to neutralize the whole of
this argument. This was the microscope. The
one/' said that great man whose language we
quote, " led me to see a system in every star.
The other leads me to see a world in every atom.
The one taught me that this mighty globe, with
the whole burden of its people and of its coun-
tries, is but a grain of sand on the high field of
immensity. The other teaches me that every
grain of sand may harbor within it the tribes
and the families of a busy population. The one
told me of the insignificance of the world I tread
upon. The other refwsms it from all its insig-
nificance ; for it tells me that in the leaves <rf
every forest, and in the flowers of every garden,
and in the waters of every rivulet, there are
worlds teeming with life, and numberless as are
the glories of the firmament. The one has sug-
gested to me, that beyond and above all that is
visible to man, there may lie fields of creation
which sweep immeasurably along, and caiTy the
Impress of the Alnngbty's Taood \^ t\i<^ xemotest
scenes of the universe. The other suggests
me, that within and beneath all that minutenesa
-which the aided eje of man has been able to
explore, there may lie a region of invisibles ; and
that, could we draw aside the inysterions curtain
which shrouds it from ouc senses, we raight there
see a theatre of as many wonders as astronomy
has unfolded — a universe within the compass of
B point GO small as to elude nil the powers of
the microscope, but where the wonder-working
Gnd finds room for the exercise of all liis attii-
butes, where he can raise another mechanism of
worlds, and fill aud animate them all with the
evidences of hia glory.
" Now mark how all this may be made to
meet the argument of our infidel astronomera.
By the telescope they hiwe discovered that no
magmtude, however vast, is beyond the grasp of
the Divinity, But by the microscope we have
also discovered, that no minuteness, however
slirunk from the notiee of human eye, is beneath
the condescension of his regard. Every addi-
tion to the powerB of the one instrument, ex-
tends the limit of hia visible dominions. But,
by every addition to the powers of the other in-
Btniment, we see each part of them more crowded
than before with the wonders of his unwearying
hand. The one is constimtlf widening the circle
1
88 THE TELBSOOPS.
of hb tenitoiy. The other is as constantly fill-
ing up iU separate portions with all that is rich,
and various, and exquisite. In a word, by the
one I am told that the Almighty is now at work
in regions more distant than geometry has ever
measured, and among worlds more manifold than
numbers have ever reached. But, by the other,
I am also told, that, with a mind to comprehend
the whole in the vast compass of its generality.
He has also a mind to cbncentrate a close and
separate attention on each and on all of its par-
ticulars ; and that the same God who sends forth
an upholding influence among all the orbs and
movements of astronomy, can fill the recesses
of every single atom with the intimacy of his
presence, and travel, in all the greatness of his
unimpaired attributes, upon every one spot and
comer of the imiverse he has formed." — Ohal-
mers^s Astronomical Discourses,
For the introduction of a passage so long, and
so well-known, the reader will find an apology
in its great beauty and appositeness. It may
also be added, that it would be impossible to sup-
ply a more appropriate preface to the subject of
the following pages. It is a link of exquisite
workmanship, connecting the two parts of this
httle volume.
1
THB MICROSCOPE AND ITS OBJECTS. 89
PART II.
THE MICROSCOPE AND ITS OBJECTS.
A MICROSCOPE is an optical instrument, by which
very small objects are magnified. By means of
it many discoYeries have been made, which are,
in some respects, even more wonderful than those
oi the telescope. We naturally associate ideas
of magnitude with power; but to discover the
infinite in the invisible, not because it is remote,
but because it is too diminutive to be discerned,
baffles all our attempts to '* find out" Him whose
greatness is as unsearchable in the minute as in
the mighty.
Invention of the microscope. — ^The microscope
appears to have been invented not long after the
telescope^ and it is probable that the invention
of the one instrument led to that of the other.
All that we can be assured of is, that micro-
scopes were first used in Germany, about the year
1621, or nearly twelve years after the invention
of the telescope. According to Borellus, who
gives the most particular details of its invention,
we are indebted to Zachary Jansen and his son
for the microscope. Others, however, claim the
honor of inventing it, particularly CQr\3L<&lv\3& I^\<6-
90 THE MICROSCOPE AND ITS OBJEOTB.
bell, a man of science and ingenuity, who invented
the thermometer; and Fontana, who professed
that he made the discovery in 1618, although he
published no account till 1 6 4 6 . Borellus informs
us that the Jansens presented the first micro-
scopes which they made to Prince Maurice and
Albert, Archduke of Austria. A minute descrip-
tion has been given of these instruments, from
which it is evident they were either compound
microscopes, or telescopes adapted to the exami-
nation of near objects by a different arrangement
of the glasses. In No. 42 of the " Philosophical
Transactions" of the Royal Society for 1668,
we have an account of a microscope made by
Eustachio Divini, at Rome, which consisted of
two plano-convex glasses, so placed as to touch
each other in the middle of their convex surfiEice.
It is described as sixteen inches long, the eye-glass
almost as broad as the palm of a man's hand,
and the tube in which it was inclosed almost as
thick as a man's leg ; it was adjusted at four dif-
ferent lengths — in the first, which was the leasts
it showed objects forty-one times larger than to
the naked eye, in the second ninety times, in the
third one hundred and eleven times, and in the
fourth one hundred and forty-three times.
About the period now referred to, M. Hart-
soeker proposed using smaW ^loWlea of ^lass.
1
THE MICROSCOPE AND ITS OBJECTS. 91
instead of lenses. A microscope, containing a
globule one tenth of an inch in diameter, may
be demonstrated to have a magnifying power of
one hundred times in diameter. Were it not for
the diflSculty of applying objects to these magni-
fiers, the want of light, and the small field of dis-
tinct vision that can be obtained in them, they
would perhaps be the most perfect of single mi-
croscopes, since they could be made to magnify
above three hundred times ; but they are now sel-
dom used. Few distinguished themselves more,
in the seventeenth century, by their microscopical
observations and discoveries, than the famous M.
Leuwenhoek, a native of Holland. His micro-
scopes all consisted of small double convex len-
ses, set in a socket between two silver plates
riveted together, and pierced with a small hole ;
and the object was fixed on the point of a
needle, so contrived as to be placed at any distance
from the lens. These microscopes were be-
queathed to the Royal Society, and on examining
them it was found that the highest magnifier in-
creased the diameter of an object one hundred
and sixty times, but that all the rest fell much
short of that power.
1
THE UOBOSCOPB ADD m
General description of Microscopa.
A brief description will now be given
which are most simple and most eoiumonly used.
1. The single mia-oscope. — Tliis amplest o(
Oill microscopes is nothing more than a con-
vex lens, whose focal distance is extremely aliod
Let A B, 6g. 18, be a double conrex lens, y «
llie object at its focus c, g the eye very near thfl
lens A B ; the rays coming I'rom the object will,
after their refraction, fall panillel upon the eye,
and, consequently, make distinct vision. There-
fore, a minute object e f, seen distinctly through
a small glass lens t. n, by the eye put close lo it,
a,ppears so much greater than it would to thp
naked eye placed at the distance n d, as this dis-
tance is greater than s c. To illustrate Ibis, let
us suppose the focal distance of the glass a b to
be half an Inch, and tlie distance b d eight inohea.
the usual distance at which we view minute ob-
jects, then the object may be said to be magoi-
Sed as ranch as eiglil lucVea cxoee4 Oat w
e a c, or iLu focul dwUnce ot xJ
31
THB MICROSCOPE AND ITS OBJECTS.
93
that is, in the proportion of sixteen to one, or six-
teen times. If the focal distance of the lens were
one-fifth of an inch, the magnifying power would
be forty times ; if one- tenth of an inch, eighty
times ; and if it were one-twentieth of an inch, the
diameter of any object would be magnified one
hundred and sixty times, which is found by divid-
ing eight inches by the focal length of the lens,
8-r^iP=160. The surface of the object will, of
course, be found by multiplying the diameter into
itself, which produces twenty-five thousand six
hundred times ; and the solidity or bulk would be
magnified four million and ninety-six thousand
times, that is, the surface multiplied by the diame-
ter. A angle microscope may be represented by
^. 19, where y is the lens fixed into a socket
with- a handle, a e a small object placed at its
focal distance from the lens, and a e the magnified
picture of the object.
Fig. 10.
84 THE MICROSCOPE AND ITS 0BJEC18.
The performance of the single microscope d
pends, in a greai mensure, on the Qlearneas nod
purity of the glass of which it la made, and oa
the ttcouraoy with whicli it is polished, sd aa to
tcep it of a true spherical Sgure. Wben eim>
pklL'd — that is, when ground and polished— ft
should be as thin as it can possibly be rendered
with a sufficient aperture. When a lens is thak,
approaching to the figui'c of a globe, it is not so
tiansparent as when thin, and the field of view
at the edges is partiy distorted. And it must
be of a sufficient diameter or aperture, that the
eye may take in a moderate Geld of view, and
Lhat there may be as little deficiency of light aa
possible. Lenses hai-e been made whose focal
length did not exceed one-fortieth, one-fifdelb,
or one-sixtjetii of an inch ; but such high powers
are difficult to be used. Sir D. Crewslcr has
remarkf d, that " we cannot expect any essential
improvcmeat in the single microscope, uoleas
from the discovery of some transparent substatKOi
which, like the diamond, combines a high re-
fractive power with a low power of ilisperaion,"
In corrL'hpondencc with this suggestion, the ^a-
mor^ h-is been of late years formed into lenue
by. Mr. Pritchard, of London. The first diamond
Jeps was completed at the end. ot \%'I4, and }m
succeeded in finishing the fits*. iianioTii iimsto-
TBS MICR0800PB AND ITS OBJECTS.
95
scope in 1826. The focal distance of this mag-
nifier, Tvhich was double convex, is about one-
thirtieth of an inch. The principal advantages
of employing diamonds in the formation of micro-
scopes, arise from the naturally high refracting
power they possess, by which we can obtain
lenses of any degree of magnifying power, with
oomparatiyely shallow curves. The indistinct-
ness occasioned by the figure of the lens is thus
greatly diminished, and the dispersion of color
in the substance being as low as that of water,
renders the lens nearly achromatic. Mr. Prit-
chard has also formed lenses of sapphire and
other precious stones, but they are not prefera-
ble to the diamond. The following table ex-
hilHts the magnif3ang powers of Mr. Pritchard*s
sapphire microscopes : —
FMlaoraainch.
/
nrr
Magnifying Power.
Linear.
/
Magnifying Power.
Superficial.
80
6,400
120
14,400
160
25,600
200
40,000
240
57,600
820
102,400
400
160,000
560
318,600
640
I \Q^,^^^
800
\ UQ<^^^
\
X
96 THE MICROSCOPE AND ITS OBJSOTB.
In mounting the diamond and sapphire lenses
there are advantages which glass lenses do not
possess. Their extreme hardness enables them
to be burnished with brass settings, which is
very difficult with those of glass. This facility
of mounting renders them more extensiyely
useful in experimental researches, from their
capability of being applied in every possible
way with regard to the object, the light, or the
eye. But it is evident that such lenses, both
from the difficulty of grinding and polishing,
and from the costliness of the material, muBt be
very expensive.
There are various simple methods of procuring
small lenses for microscopes, some of which
may be here stated/ Take a small slip of win-
dow glass, about one-tenth of an inch broad;
melt it in the flame of a lamp, then draw it oat
into fine threads, then hold one of these threads
with its extremity in or near the flame, till it
runs into a globule. The globule may then be
cut off and placed above a small aperture, so
that none of the rays which it transmits pass
through the part where it is joined to the thread
of glass. Lenses composed of fluids have also
been made, which are frequently useful where
better microscopes are not at hand. Take up
a drop of water on the point of a pin, and place
THE MICROSCOPE AND ITS OBJECTS. 97
It in a small hole in a thin piece of brass^ about
one- twentieth of an inch in diameter. The hole
should be in the middle of a small spherical
eayity, about one-seventh of an inch in diameter,
and a little more than half the thickness of the
brass, which should not exceed one-sixteenth of
an inch in thickness. On the opposite side of
the brass should be another spherical cavity,
half as broad as the former, and so deep as to
reduce the circumference of the small hole to a
sharp edge. The water being placed in these
cavities will form a double convex lens with
unequal convexities, which will produce' a pretty
high magnifying power. A better substitute
for water is a drop of very pure and viscid
turpentine varnish, which may be taken up on
the point of a piece of wood and dropped upon
a piece of thin and well-polished glass. Sir D.
Brewster describes the following as the best
method of constructing fluid microscopes : — Take
Canada balsam, castor oil, or pure turpentine
varnish, and drop either of them on a piece of
glass, the surfaces of which are parallel, when a
plano-convex lens will be formed. Their power
may be varied by the quantity of the fluid em-
ployed, or by allowing the plate of glass to be
horizontal with the drop above or beneath it :
if the plate be uppermost, the gr«N\V3 ^^ ^^^^
1
98 THE MICROSCOPE AND ITS OBJEOTB.
fluid will make it more convex ; if the drop be
above tbe plate, the lens will be flattoied.
When turpentine is used, it soon becomes indu-
rated, and, if kept from dust, very durable. Sir
David informs us, that he has made both the
object and eye-lenses of compound microscopes
in this manner, which performed extremely well,
and lasted a considerable time.^ A single re-
fleeting microscope may be formed by i^ concave
speculum, having the object placed on its axis,
and nearer to the surface of the reflector than
the focus, when an enlarged view of the object
will be seen on looking into the mirror. This
instnunent may be employed to enable a person
to view his own eye, and will show a magnified
representation of the ball, the pupil, the iris,
and the ramifications of the blood-vessels. On
the same principle, if the reflector be large, for
example, six inches in diameter, the whole head
and face may be seen magnified three or four
times in length and breadth, and above tien
times in suiface. There is a species of lens,
sometimes called the Coddington lens, formed
of a piece of glass nearly half an inch in thick-
ness. The upper and lower surfaces are convex.
The sides are hollowed out, giving the lens
^ Treatise on New Philosopliical Instruments, pagei
414, 416.
THE MICROSCOPE AND ITS OBJECTS. 99
somewhat the shape of an hour-glass, and re-
ducing the stem to a very small size. These
lenses are of a very short focal distance, have a
great magnifying power, and serve either as
single microscopes, or for the object-glasses of
compound ones.
There are various modes of fitting up single
microscopes, some of which are complex and
expensive. The following plan may be recom-
mended as both simple and convenient. Fig. 20
(p. 100) represents the mounting of a single mi-
croscope. K represents the box containing tho
whole apparatus. On its top there is a hollow
screw, for receiving the screw that is in the
bottom of the pillar a. d is a brass pin that
fits into the pillar. On the top of this pin is a
hollow socket to receive the arm that carries
the magnifiers ; the pin is to be moved up or
down to adjust the lenses to their proper dis-
tance from the object, e the bar which
carries the magnifying lens, which fits into the
socket X. This arm may be moved backwards
and forwards in the socket x, and sideways
by the pin d, so that the magnifier, which is
screwed into the ring at the end e, may be
easily made to traverse over any part of the
object that lies on the stage or plate b. f f is
a polished silver speculum, with a c.otc^%^\k«^
160039
plftced at 11 LLi t (\1 h L J ^ hJ for this
purpose, riie sUter Bpeculum sciens into tbe
arm e, as at f h th« semicircle which Eupports
the mirror i e the stage or the plane on which
tlie objects are to be placed, l a pair of nippen
which are fixed on the stage by the pla k
ivory slider which occasionally screws te J
THE MICROSCOPE AKD ITS OBJECTS. 101
point of the nippers. The silver speculum is
intended to throw light on the upper surface of
an opaque object ; but when transparent objects
are viewed, there are other lenses which may
be used without the speculum. Additional
apparatus is connected with this and other
microscopes, which it is unnecessary here to
describe.
2 . The compound microscope. — ^When a micro-
scope consists of two or more lenses or specula,
it is called a compound microscope. In this
microscope the im>age is contemplated instead of
the object ; one of the lenses of which it is com-
posed forms an image or picture of the object,
as in the telescope, and this image, in a magni-
fied state, is viewed by an eye-glass, which pro-
duces an additional magnifying power. Let l n,
^g. 21, (p. 202,) represent a double convex lens,
and o B a small object, so applied that the pencils
of rays which emerge from it and pass through
the lens may converge to their respective foci,
and form an inverted image at i m. This image
will be so much larger than the object, in pro-
portion as its distance exceeds that of the object
from the lens. For example, if the distance of
the lens l n from the object o b be half an inch,
and the distance l m, where the image is formed,
be seven inches, the image wJft. \» toxsNftws^
THE MICROSCOPE AKD
^
times larger than the object ; and if it be vien
through the lens f o, which suppose to be i
inch, it will ag^ be magnified eight times,
the prindple of the single microscope, and i
whole magnifying power will be 8X14=]
times. But the pencil of rays emitted fron
in the object, and made to converge by the 1
to M, proceeds afterwards diverging towards
and, therefore, nerer arrives at the lens 7 a, i
enters the eye at e. Oii\y XVb i«,^«^!D^-\RQa
MH^I
from the poiats o and ft will be received o
lens s a, and by it be carried to the eye ; the
parts of the imnge i and ni will be yisible, but
those situated towards i and m will not be seen.
This quanUty (i in) of the image i -a ia called
the _fieM of vtew, which is comparatively small
when only a single glass is used. In order to
enlarge the field of view, it is requisite that a
broad lens, s e, fig, 22, be interposed at a small
distance from the focal image ; for by tbat means
the pencil a m, which would otherwise 113ve pro-
ceeded towards h, is refracted to the eye, as
shown in the tigure. In the same manner, the
other extreme of the imag'e is seen at q, and the
intermediate points are ulso rendered visible.
On these oonsideratJons it is that compound
microscopes are usually made to consist of an
object lens, l s, by which the image is forined
and enlarged, na amplifying lens, d b, by which
the field of view is enlarged, and an eye-glaaa,
F c, by which the eye is allowed to approach
very near, and to view the image under a great
angle of apparent magnitude. For similar rea- .
sons tliree, and sometimes fom' eye-glasses s
Bubstituted in place of the amplifying lens.
Having briefly described the theory and pria-1
'■ ciple of this microscope, we shall now pve a
description of the finished inGlmmc'cA, w\& 'Cuk
THE MICROSCOPE AND ITS OBJECTS. 105
way in which it is used. The large figure, fig.
23, represents the body of the microscope ready
for use, which, including the pedestal, is from
twelve to fifteen inches in height. In this figure
it is represented as consisting of three tubes. In
the large tube, a, the smaller one, b, slides up
and down. At the upper part, a, one or two
eye-glasses are contained, and at some distance
beneath them the amplifying lens is placed. At
the lower part, 6, the object-glass is placed, %nd
the small tube which contains it is connected
with the tube b, by which it is made to slide up
or down, to adjust the focus to the eye. Below
the object-glass is c, a kind of spring to receive
the stiders, which may be occasionally taken out,
and a plane glass laid across the opening in the
stage on which any small object may be laid.
D is the pedestal on which the instrument stands,
c is a glass concave mirror, which turns in all
directions, to reflect the light from a candle, or
from a window, through the hole c. Fig. 24
represents nippei's for holding insects, or other
small objects. Fig. 25 is a small glass tube,
capable of containing a live fish, when observing
the circulation of the blood in its tail. Fig. 26
repesents one of the sliders for holding objects,
vhich are placed between two pieces of talc, or
two thin slips of glass. Fig. 2*1 laalxoWo^ <iQV!^^^
106 llll!: MICROSCOPii AND IT8 OIMKOTS.
to be placed occasionally under the stage d, to
diminish the quantity of light. Fig. 28 is a pair
of brass forceps, to take up a minute object
Fig. 29 represents a round piece of glass, to
which is fitted a concave glass, for the purpose
of confining animalcules, and other small living
creatures, for minute inspection.
Compound microscopes have been much im*
proved of late, by using small achromatic lenses
foi-^the object-glasses. They have been made
as small as one-fifth, one-fourth, one-half, and
one inch focal distance, and sometimes two or
three of them are occasionally combined together,
which produces a very high magnifying power,
with great distinctness. But such lenses add
considerably to the expense. About ten yean
ago £1 3«. was the cost of one of these lenses
one and a quarter inch focal distant, and those
which were of a shorter focal distance were
charged at two guineas and upwards. A person
who feels himself unable to purchase an expen-
sive compound microscope, may construct a
pretty powerfid one for a few shillings, by at-
tending to the following directions : — Procure
for the object-glass a lens about half an inch
focal distance ; another for the amplifying lens
two and a half inches focal length and one and a
half inch diameter ; aivd a third ^lass one inch
107 ^H
distance, to be placed next the eye. The
at which these glnascs should be placed
each other are as follows : — The object-
half an inch focal distance, should be
i at the end of a small tube nest the
jcct, and the aperture or hole that lets in the
"it should not eiceed one-tenth of an inch in
meter. At the distance of about seven inches
B this glass the nmplifying lens should be
Midi and the glass next the eye, one inch focnl
Ijuioe, ehould be placed about one and three-
.n inch from the amplifying lens.
lb a microscope, reckoning the combined eye-
gses to magnify the image six times, and tho
ject-glass to magnify the object fourteen times,
" produce a magnifying power of eighty-four
B ui lineal dimensions, and in surface seven
busand and fifty-six times — a power which will
ow a small creature, such as a flea, as if it were
[ht and a half inches long and of a. eorrespond-
f breadth, and will bring to view all the larger
ecies of animulcules. The stage and its sup-
irta may be made of wood, and the tubes of pa-
rot very tlun pasteboard. The tube 5,{p.l04,)
which the eye-glasses are placed, should be
kde so as to pull out occasionally, to increase
between the eye-g\aaaea awi fee-
tet-ghae, and consequently t,\\e TOao;E&"3\'wf,
I
108 THE MICROSCOPE AND ITS OBJECTS.
power. Any person with mechanical talent
easily make such an instrument at a trij
expense. The compound microscope is n
pleasing in its use than the single microscc
it has a larger field of view, and the eye is
so much strained as in looldng through i
small lenses.
3. The solar microscope, — This microscop
constructed in the following manner. Ii
Fig. 30.
closed window shutter, or in a board fitted
the window, make a hole about three inche
diameter, through which the sun may cac
cylinder of rays, a a, into the darkened ro
^^, 80. Into this hole place the end of a ti
containing two convex glasses and an obg
namely, a convex glass, a a, of about two inc
diameter and three inches focal distance, is t(
placed in the end of the tube, which is put
the hole. The object, b b, \& ^\sa^ ^\^Q^t
THE MICROSCOPE AND ITS OBJECTS. 109
nd a half inches from the glass a a. If the
bject be a living animal it must be put between
wo concave glasses. A little more than a quarter
f an inch from the object is placed the small
onvex lens c c, whose focal distance may be
bout a quarter of an inch. The tube may be
o placed, when the sun is low, as that his rays,
. A, may enter directly into it ; but when he is
ligh, his rays, b b, must be reflected Into the
ube by the plane mirror c c. Things being in
his state, the rays that enter the tube will be
onveyed by the lens a a towards the object b b,
\Y which means it will be strongly illuminated,
nd the rays d, which flow from it through the
VOM e €, will form a large inverted picture of the
bject at D D, which being received on a white
yreefn, will represent the object magnified in
mgth, in proportion of the distance of the pic-
ire from the glass c c to the distance of the ob-
ust from the same lens. Thus, suppose the dis-
ince of the object from the lens to be half an
icb, and the distance of the image fourteen feet,
r <me hundred and sixty-eight inches, the object
fill be magnified in length and breadth three
nndred and thirty-six times, and in surface one
andred and twelve thousand, eight hundred
nd ninety-six times.
In fig. 31, some of the parts of this instrument
110 THE MICKOSCOPB AND ITS OBJECTS.
are more particularly represented. The sq
plate, b c d, is attached to the wmdow shi
by the screws ef. The mirror g is mount6(
a wooden frame, and may be elevated or
pressed by a screw at d. A rotary motk
communicated by a pinion and handle $i c. '
first lens is placed in the tube a, immedisi
adjoining the mirror. Another tube, m, Ib
tached by a screw at n, and contains the oi
lenses for magnifymg the object, and the n
THE MICROSCOPE AND ITS OBJECTS. Ill
work k I for adjusting the' focus of the instru-
ment. The objects are introduced at i. When
lenses of high power are employed at A, they
are now constructed on the achromatic principle.
This instrument is not so much used as for-
merly, in consequence of the invention of the
oxyhydrogen microscope, which is not depend-
ent on the sun, but may be used either by day
or by night, provided the room be darkened,
the oxyhydrogen light being substituted for that
of the sun. This is the microscope which is
now exhibited in lecture-rooms, and in our Poly-
technic Institutions. It may not be improper
here, to give a hint to some persons not much ac-
quainted with such exhibitions. One of the ob-
jects shown by this microscope (the oxyhydrogen)
is the appearance of a heterogeneous mass of
animals, which appear to be fighting with each
other on a very large screen, intermixed with
T^etable fibres. It has been taken for granted
by some spectators, that these animab were all
contained in a drop or two of water, and that
they consorted together in the manner repre-
sented. This is by no means the case ; no such
associations are to be foimd in the animalcular
world. A number of small animals of dififerent
kinds, most of them visible to the naked eye,
are collected by the exhibitors, and put into a
112 THE MICROSCOPB AND ITS OBJKOTB.
small glass vessel, perhaps an inch or two in
diameter, along with water and a few vegetable
fibres. It forms a strildng exhibition, but p^-
sons should beware of deducing from it erroner
ous conclusions.
4. The lucerrud microscope. — This instniment
was invented by Mr. George Adams, an optician
in London. It consists of a hollow pyramidal
box of mahogany, which forms the body of the
microscope. Fig. 32 exhibits a view of this in-
strument, mounted to examine opaque objects.
6 is the large pyramidal box, supported firmly
on the brass pillar n, by means of the socket m
and the curved piece e, a is a guide for the
eye, to direct it in the axis of the lenses ; it con-
sists of two brass tubes I, one sliding within the
other, and a vertical flat piece, at the top of
which is the hole for the eye. The inner tube
may be pulled out or pushed in, to adjust it to
the focus of the glasses. The vertical piece
may be raised or depressed, that the hole through
which the object is to be viewed may coincide
with the centre of the field of view. At the
small end of the cone is placed a tube, whieh
carries the magnifiers, one of which is repre-
sented at c ; the tube may be unscrewed occa-
sionally from the wooden body. Beneath the
cone is placed a long square bar, which paaeei
THE MICROSCOPE AND ITS OBJECTS. 113
through, and carries the stage or frame that
holds the object ; this bar may be moved back-
wards or forwards, to adjust it to the focus, by
means of the pinion k. A handle, with a uni-
versal joint for turning the pinion, is shown at o.
The stage h, for opaque objects, fits upon the
bar by means of a socket, and is brought nearer
Fiff. S9.
to or farther from the magnifying lens by tum-
mg the pinion h. At the lower part of the stage
there is a semicircular lump of glass, g, which
ifl designed to receive the light from the lamp,
and to throw it on the concave mirror/, whence
it is reflected on the object. The upper part of
the ojmque stage takes out, t\^t \\i^ %Xaj^^ Vst
8
114 THE MICROSCOPE AND ITS OBJECTS.
transparent objects may be inserted in its place.
Between the exterior of the two lenses at the
larger end and the eye of the observer, th^ie is
placed a plate of glass, rough ground on one
side, which serves as a screen to receive the rays
of light proceeding from the object whose repre-
sentation is to be viewed. An Argand lamp, or
the oxyhydrogcn light, is placed beyond the ob-
ject, before the glass lump g.
By this instrument, opaque objects may be
seen with ease and distinctness. The beautiful
colors ^vith which most of them are adorned are
rendered more bnlliant, without changing in the
least the real tint ; and the concave and convex
parts retain also their proper form. The facility
with which all opaque objects are applied to this
instrument is another considerable advantage,
and one almost peculiar to it. The lucenud
microscope does not in the least fatigue the eye ;
the object appears like nature itself, giving ease
to the sight and pleasure to the mind ; and there
is no occasion to shut the eye that is not directed
to the object. The outlines of eveiy object may
be taken even by those who are not accustomed
to draw, while those who can draw well will re-
•
ceive great assistance. Transparent objects as
well as opaque may be copied in the same man-
ner. This instrument may \)^ \i&ed ^t any time
THE MICKOtiCOPE A^V ITS OBJECTS. 115
oi the day, but the best effect is by night, in
which respect it has a superiority over the solar
microscope, which can only be used when the sun
shines. Such are some of the properties of tbe
lucenud microscope, as stated by the inventor.
Besides the microscopes we have already de-
cribed, different forms of this instrument have
been constructed on the principle of reflection,
by a combination of speculums both convex and
concave. These microscopes were constructed
as early as the year 1738, by Dr. Smith, Mr.
Baker, and others, but they had been abandoned
for many years, till, in the year 1815, Amici, a
Frenchman, directed his attention to their con-
Btruction, and greatly improved them ; and they
were still further improved in England by Dr.
Gonng and Mr. Cuthbert ; but owing to the
difficulty in constructing the reflectors, and the
great trouble in managing them, they again fell
into disuse, and even Amici himself returned to
htB former experiments with achromatic object-
glasses.
If it be asked which of the microscopes now
described we would recommend for making re-
searches into the mmute parts of nature, we
answer, without hesitation, the compound micro-
dcope furnished with achromatic object-gla^aea,
Tbe compound microscope as no\Y \m\iiQ)N^, \a
116 THE MICROSCOPE AND ITS OBJEOT6.
use the words of an eminent optician, "1
within the last sixteen years, been elevated fi
the condition in which it was previously fot
to that of being the most important instrunQ
ever yet bestowed by art upon the investigi
of nature." The application of achromatic
ject-glasses to compound microscopes has o
been attempted within the last twenty-six ye
In 1824, the late Mr. Tulley, of London, 8
ceeded in making the first English achromi
object-glass for a compound microscope,
was composed of three lenses, and was cape
of transmitting a pencil of rays of 18°.
soon after constructed another combination
be placed in the front of the first mention
which increased the angle of the pencil to S
Mr. Tulley's object-glass exhibited a flat fi«
and was perfectly corrected ; to it was app
an eye-piece, by which the magnifying po'
produced was one hundred and twenty diamet*
but when the second combination was add
the power was increased to three himdi
These object-glasses have since been impra
by Messrs. Lister, Powell, Ross, and Sm
Their focal distances vary from one inch an
half to one-eighth of an inch, and they may
used either separately or m combination. Soi
times tiiree seta of ^eoi «c^ <^csii!^s«^ V^i^
THB laOROSCOPB AND ITS OBJECTS. 117
which produces a very powerful effect. Mag-
nifying powers equal to one thousand two hun-
dred diameters have thus been obtained with
great distinctness ; that is, the surfaces of objects
have been magnified one million four hundred
and forty thousand times. Some of the powers
thus obtained have been equal to even two
thousand diameters, and consequently the sur-
face magnified four million times. But such
instnunents, as formerly stated, are expensive.
Objects to which the microscope may he applied.
Every part of creation demands our atten-
tion, and proclaims the power and wisdom of
the Creator. The microscope has shown to
UB these perfections in objects which the unas-
sisted eye has never seen, no less than in those
which may attract our notice in all the walks
of life. It has unfolded to our view wonders
unknown and unthought of in former ages.
Three hundred years ago, who would have
conceived it possible to distinguish myriads of
living creatures in a single drop of water ? Or,
that blood could be distinctly seen circulating
through the veins and arteries, smaller than the
finest hair? Or, that not only the exterior
form, but even the internal structure of the
visoera, and the motion of the VxvWiox ^^^>
118 THE MlCltOBC'OPE *SIJ ITS OltJECT^.
sLouid be rendered perceptible to the aght?
Or, that numberless species of animnted bcingi
should he mcide visible to the eye, though so
minute that a million of them are less than b
grain of sand ?
The various sections of animal and vegetable
life are full of beauty, and in their minutest de-
tails exhibit a completeness and a finish infinitelj'
transcending tlie most exquisite and ndtnlred
pieces of art. The scale of a sole, so small as to
be overlooked by us, is a work of moat admintbiB
regularity and delicacy. It is a kind of wch,
with a number of small points at one end,
which fasten it to the hack of the fish. TilVK
is not a singie fish whose scales are not inora
beautifully woven than any texture whioh ia
found in the finest handiwork of man. The
fibres that compose the scale of a pike are
formed in a manner quite different from those
we admire in the scale of a cwrp or a perch;
still one order is invariable in all the scales <rf
the same species. Equal regularity b found in
tlie structure of the feathers of birds, in the
fibres of the flesh of animals, in the grain of the
several kinds of wood, and in the figui'es of the
tJ'ifferent salts. The dust on the wing of a
moth or a bullerfly. a single ^omXAe <A -wVuio,
M so minute as to be m-vi*ib\e,"\a lo-aRa.. -*»«
THE MICROSCOPE AND ITS OBJECTS. 119
magnified, to be a beautifully-formed feather,
and exhibits the most delicate and admirable
arrangement in all its parts. In a moth there is
a configuration entirely distinct from that of a
butterfly ; each species has feathers of a different
form from those of another. The same variety
and exquisite mechanism prevails in every de-
partment of the vegetable kingdom.
The following objects, among many others,
may afford amusement and instruction to those
who are possessed of microscopes : — ^the scales
of fishes ; the dust on the wings of butterflies,
moths, gnats, flies, and other insects ; the flea,
and mites in cheese ; the eels, serpents, or little
worm-like animals found in vinegar and paste ;
the animalcules existing in infusions of pepper,
as well as of hay, grass, flowers, and other vege-
table substances ; the eye of the house-fly, the
dragon-fly, and of various other insects; the
legs of spiders ; the claws of beetles ; the wings
of small flies ; the eye of a lobster ; slices of
broom, lime-tree, dogwood, and oak ; transverse
sections of plants of various kinds, every one of
which has a different configuration from an-
other ; the farina of flowers, particularly of the
sunflower; the leaves of trees, plants, and
flowers ; the fibres of a peacock's feather, and
the feathers of other, birds ; the hnm&xv \v^x \
120
the hair of a mouse, ajid llie hair of on Indite
bat ; the sting of a bee or a wasp ; the stings d
a nettle ; small files which infest fruit and trees;
the beard of a wild oat ; seeds of poppies tmd
other small seeds ; mouldiness, which is a spe-
cies of vegetatiim, or a forest of mushrooms;
the small nimble insects existing among pinb,
roses, and sunflowers ; water spiderE^, not la>^
than a grain of sand, found in ditehes : the silk-
worm in its rarious transformations ; the njmph,
aurelia, or chrysalis of moths, butterflies, and
other insects ; the proboscis of a butterSy,
which winds romid in a spiral fonn like the
spring of a watch, serving both for mouth and
tongue ; mosses of all kinds ; sponge, reckoned
a plant-animal, composed of minute vessels m-
sembling veins and Ftrteries ; grains of sand,
which are of vanoua forms, having al! numeroos
sides and angles, some of them finely polished !
the flakes of snow before they melt : the tmls of
fishes, the flns of water-newts, and the webs
between the toes of frogs, in which the droa-
laljon of the blood may be beautifully seen ; and
fresh-water polypi, witli arms in theform of lionw.
The above are only a few specimens of ta&
thousand objects in the minute parts of creatJon,
which display beauties, contrivances, and in-
MtaaetB ej ditine meehaiusm. of ^luefa va-
- TflS MICROBCOPB AND ITS OBJECTS. 121
who has not looked at them through the micro-
scope can form any adequate conception. There
is, in fact, scarcely a particle of matter in crea-
tion, in which this instrument does not show
something worthy of being admired. In addi-
tion to natural objects, however, we may further
mention the following artificial productions,
which afford entertaining materials for micro-
scopic observation. 1. The silver- tree ; the pre-
paration of which is as follows : — Dissolve a little
silver in a small quantity of aquafortis ; thpn
add twice the quantity of common water to it.
When it is applied to the microscope, a little of
it should be dropped on a plane glass, and a
short piece of small brass wire put into it ; imme-
diately trees will appear growing, till they have
spread as far as the liquid extends. 2. The
eryiiallizaiion of salts : — Dissolve a little sal-
ammoniac in common water, place it upon the
glass as stated above, and while viewing it,
hold a hot iron near the glass, in order to make
it more expeditious in evaporating. As soon
as evaporation takes place, appearances are pre-
sented like the branches of trees, in the most
beautiful variety. Every different kind of salt
forms a new arrangement and a different figure.
Among the multitude of ob^eeXfe -w^kvs^ \i^\xsK.
preaenta for the employment o< ^"fe xmvrx^^^^^'V^^
1S2 THE aaCBOSCOPE AXD nS OUECIS.
our limi'^ wiil p-erz:;: us lo select only a few f<
pfjfilf.-.-'ijr DOiic*. Wc shall commence with
descripiion of a few species of
AyiMALcuLE?. — Pnis lerm is now general];
used to distinofuish animals of a size so diminn
live that their true figure cannot be discerned
without the assistance of glasses; and mor
especially, it is applied to such as are altogethe
invisible to the naked eye. By the microscop
we are brought into acquaintance with nei
tribes of the li\'ing world, and innumerabi
animated beings, which, from their minuteness
would without it have escaped our observation
How many of these invisible tribes there noay b
throughout the air, the waters, and the earth, i
still unknown, but they doubtless far exceed th<
number of all other classes of li\ing creature
combined. To know that there are myriads oi
atoms, endued with vitality, existing in a singk
drop of water, executing all their various func
tions and evolutions with as much rapidity anc
case as if the range afforded them were bound
less as the ocean, must powerfully interest ever]
mind which takes pleasure in the works of God
It is almost impossible to convey a correct idef
of the various shapes of these singular forms of
life to those who have not actually beheld them
2lHiy appear to have little or no similarity to the
THE MICBOSCOPE AND ITS OBJECTS. 123
other diversified orders of animal existence.
Some of the smallest appear merely like moving
points or atoms ; the large ones exhibit an as-
tonishing variety — some are hke spheres, others
are ^g-shaped ; some are like hand-bells, others
are like wheels turning on an axis ; some repre-
sent fruits and vegetables of various kinds,
others resemble eels, serpents, and snakes ; some
are like double-headed monsters, and others like
cylinders ; some have the appearance of funnels,
tops, pitchers, and flasks, others are worm-like ;
some have horns, fins, and feet, others resemble
small fishes, playing in the rivers or the sea;
some are like long hairs, a hundred times longer
than they are broad, other are like spires and
enpolas ; some of them are almost visible to the
naked eye, others so small that a human hair
would cover more than a hundred of them ; while
millions of millions of them might be contained
within' the compass of a square inch. They,
however, possess {Peculiar habits, adapted to
their respective forms. While some move
through the water with the greatest rapidity,
darting, leaping, or swimming, others creep or
glide along, and many are so passive, that it
requires patient observation to discover any of
their movements. We may now give a brief
description of some individual speciea of auimal-
cnles.
124 THE MICROSCOPE AND ITS OBJECTS.
1. The Monads. — This genus of animalci
includes the smallest forms in which a volunt
motion has heen observed under the most po¥
ful microscopes. Motion appeared to be
only property of life they possessed, till
Ehrenberg, an eminent observer of animalci
existence, demonstrated an organization equi
perfect with creatures of much lai^er dimensi<
Their forms are spherical, or cylindrical, and t;
are colorless, and transparent as the clearest ci
tal. They increase by a spontaneous division
the parent into two or more parts, and these p
again divide, as do also the young when i\
have attained their full size. These animalci
are chiejfly interesting from their extreme mini
ness. They form the limit of man*s acquaints
with animated nature. Their diameters vary fi
the twenty-four thousandth part of an inch to
twelve hundreth. What is called the end ma
is so very minute that its existence cannot be <
covered in the best instruments with a less po^
than four hundred linear, or one hundred i
sixty thousand times in surface. They are ol
so abundant on the surface of infusions that mi
millions in a single drop may be taken up on
head of a pin. If we take some of these anin
cules, and suppose them to be arranged u
]me of only one incb in lengtb, it \70uld reqi
IHS MIORO.iCOPS AND ITS OBJECTS. 125
nine thousand six hundred to fonn it ; so that a
cubic inch would contain eight hundred and
eighty-four thousand seven hundred and thirty -
m millions. Some of these monads are found in
▼aiious vegetable infusions, and are very numer-
0118 about the infused stalks of the spider- wort.*
2. Animalcules found in infusions of pepper, —
If the bottom of an open vessel be covered to
the depth of half an inch with black pepper,
grossly bruised, and rain or river water be poured
in until it rises above the pepper about an inch,
and if the water be well stirred and exposed to
the air, in a few days a little pellicle or skin will
be perceived on its suiface. This skin, examined
by the microscope, will be found to contain mil-
lions of animalcules, scarcely discernible at first
by the greatest magnifier, but continually growing
la^r, till they attain their full size. Their
nombers, too, will every day multiply, and at
length the whole fluid will seem alive. About
the quantity of a pin's head of this scum, taken
up with the point of a pen, or a small hair pencil,
and applied to the microscope, will show several
sorts of animalcules, differing both in size and
°For a more particular account of these minute
animalcules, and their different species, the reader is
referred to "Pritchard's Natural History of Animal-
oules."
V2ti TUB M1C'KO«OOI'K AND ITS OUJEfltl.
in ah«pe. The following iire somi? of their
varieties ; —
Fig, 33 represents the largest kind. Tin
length of the body is about the diameter of a
small hair, and three or four times more than Ha
breadth. It ia very thin and transparent, but
that side which appears to be tbe back is darker
than the other. They frequently turn themselves
in the water, and show both faaek and belly, aa
seen in figs. 1, 2. The edges of the body are
fringed with a groat number of exceedingly mi-
nute feet, which are chiefly perceptible about l^e
two extremities. At one end, there are likewise
some bristles, longer than the feet, resembling «
tail. The motion of these animalcules is swift;
and by their turns, returns, and sudden slope,
they seem to be continually hunting about fv
their prey. They cnn employ th«r feet ia run-
ning as well as in swimming ; for, on put^Dg R
hair among .them, they often creep along it from
end to end, bending in several strange postoiM.
There is another kind of animalcule in this
infusion, whose length is about onc'third of a
hair's breadth, with tails five or six times as Img
and sometimes longer. Kig. 34, No. 1. exhituts
one of them with the tail extended. No. 2 re-
preaeats siiotber of them, w'A\i\te \«i'm «^w,x«m>
like form, which is very common. Ocswasn^'i,
; MICKOSCOPE AND I
]28 THE MICROBCOI'K AM) ITS OBJECTS,
when they lie still, tliey thrust out or pull bactr
again their bearded tongues. A Ihird kim],
about the size of the last, but -without taiU, ap-
pear sometimes in an oval shape, tts in fig. If,
No. 1 : and sometimes a little longer, rusembUng
» flounder, as So. 2. Their little feet may be
plainly seen when the water is just evaporating,
for (hen they move very swiftly. Now and then
two of them are seen conjoined, as at No. 9. A
fourth kind appear like slender worms, Bfty ttmea
as long as broad. Their thickness ia about the
one-hundredth part of a hair, and they Bwim
with the same facility backwards as forwardB,
A fifth kuid is so exceedingly small that a hun-
dred of ihera in a I'ow would not equal the dla-
meLcr of a grain of sand, and consequently &
million of them are but equal to a grain of sand
in bulk. Then- shape is almost round.
3, 77ie eeli in pasile and rinegiT, — To prooure
these, boil a little flour and water, and meh
paste as bookbinders commonly use. It shottld
neither be rery stiff nor very watery, but of ■
moderate consistence. Expose it to the Open
air in an open vessel, and prevent its hardening,
or becoming moldy on the surface, by beating
it well together. Aftt'T some days it will turn
sour, and then, if esamined a\:X*.ri>A\c\^, iid^-
ludes of small, long, riendet, -wti^'^oii% wnmi
1 IIB OBJECTS. 11
cules will be discerned, which increase daily in
ate. To promote their deveiopment a. drop of
Tinegar may now and then be let fall upon 111
paste. After tlie etls are once produced, th^i
may be kept ail the year by applying to
lasionally a. little vinegar and
may be taken to the microscope on a piece
! or thin glass, a drop of water for them
im in being previously provided. They
Tcry entertaining objects. Sometimes the
tion of their internal parts may be distiDguisbed.
la. vinegar itself, after standing a few days UU'
covered, especially in summer, a epedes of
will frequently be found. The figure of
eel-Uke animalcules is shown at fig, 36.
4. Anrmalcuhg in infmions of ha>j,
oat*, tslieai, a>id other vegetable produeli
When the above substances are infused in water,
aftur some days a sort of wbidsh scum will ap-
pear upon the surface, which, examined by a
microecope, will be found to contain an immenae
number of living creatures, of vuiious sizes and
forms. The most common is an oval animalcule,
komewhat in the shape of nn emmet's egg, as
sbown in fig. 37. They are extremely nimble,
and in continual motion backwards and forwards;
but sometimes they stop on a sudden, and t\
round on their axis numberless times, and
1
of
i. th^^^_
a thM^H
ieced^^^l
hem.^^^H
i«y "fl^l
luisbed. '
of eels
ternately in diftei-ejit directions, with surprising
velocity.
In tlic summer season, the water that Is stag-
nant in small pools and ditches appeara frequently
of a greenish, and ocvasionally of a reddish hue.
On examining it by the microscope, it is found
that immerse multjtudea of onimnlcules sro
crowded together on its surfaue, ^vbg it a, color-
ed appcamnce. The bodies of these animalcules
are oval, and transparent at both ends, bat tbc
middle is either green or red. There is reason
to believe, that in one of those ponds or ditchea
the number of living creatures enjoying a hap-
piness suited to their naturiis, exceeds thai of all
the human inhabitnnis peopling the globe, tba
liquid whiuli drains from dunghills, presentll^ S
deep brown color, is sometimes eo thronged trilb
animalcules, that it soems to be uU alife, Bod
must be diluted with water before they cwi ht
sufficiently separated to distinguish their'Turinoi
kinds. Amoug these is sometimes found a
species represented in tig. 38. Their middle
part appears daik, and beset with hairs, but
both ends of ihem are tinnsparent. Their tsib
are tapering, with a long sprig at the extremity,
and their motion is slow and waddling.
Our limits will not penmt us to prosecute this
eubjuct much further. We miiy just i-emaric
THE UIOKOSCOPE AND ITS 0BJ£CT8. 131
that an infusion of any herb, grain, fruit, flower,
leaves, or stalks of any description of vegetable,
in common water, will be found, after a few days,
to contain animalcides in immense numbers, and
of a species peculiar to the diiOferent substances
which are infused. M. Joblot, of Paris, has given
us a description of numerous experiments he
made on this subject. He examined the infusions
of pepper — black, white, and long — of senna,
pinks, blue-bottle, roses, jasmine, raspberry
stalks, tea, barberries, fennel, sage, marigold
flowers, sour grapes, mushrooms, and rhubarb,
and found different animalcules. Hay, new and
old, abounded with many kinds. Rhubarb,
mushrooms, sweet basil, and citron flowers, had
their particular animalcules. The anemone
afforded a very wonderful species, with a satyr's
face upon the back. Celery produced many
kinds, as also did wheat-ears, straw, rye, oats,
and Turkish com. Oak-bark, new and old,
afforded great variety. Some of these infusions
M. Joblot kept a whole year, and observed that
not only each infusion had animalcules of shapes
quite different from those in others, but likewise
that in the same infusion different kinds of
animalcules appeared at different times.
5. Description of some animalcules of uncom-
mon forms. — In all the productions of iva.tMXA
132 THE MIC'ROgCOPB AKD ITS
ihere is a wonderful diversity, particularly in the
forms of animalcular life. An infusion of ane-
mone, prepared after tlie oMlioary n
cold water, at the end of eight days will t^ord
a new and uncommon aniraaluule, which is repre-
sented at fi^ 39. All the surface of its back is
t5overed witli a very fine mask, in the form of b
kuman face, perfectly well made. It has three
feet on each side, and a tail coming out from
under llie mask. Another curious nnimaleide,
found in an infusion of hay, is represented at
fig. 40. A shows its head, b its forked tail, c its
heart, which may bp seen in a regular mo^esa,
and D its intestines. When this creature reeb,
it generally opens its mouth rery wide, a
Ita lips, which it moTes quickly, are fumirfied
with hairs. There are ringlets lying i
another round its hod}'. Another animalcolf^
which bears a certain resemblance to this, waS
found in an infusion of pinks, jasmine, and ottiw
flowers. It is represented at fig. 41. It differs
from the one above described, in being longer, in
il3 tail being composed of three points instead
of two, in hflvmg two little arms, l m, one on eneh
side of its heart, marked a, in Its intestines, S,
being without any visible separation, and in
having neither ringlets, teeth, nor haii« in iU
THE MIOROSOOPX AND ITS OBJECTS. 188
Another curious animalcule is found connected
with duck-weed roots. This little creature is
represented at fig. 42. It has two wheels, d e,
with a great many teeth, or notches, coming from
its head, each turning round upon an axis. At
the least touch it draws the wheel-work into its
body, and its hody into a sheath, after which it
appears as in fig. 48. But when all is quiet,
it tbmsts itself out again, and the rotation of the
wheel-work is renewed. One of these animal-
cules has heen noticed whose case seemed com-
posed of minute globules, as a, ^g. 44, and in
this the wheel-work, c, was discovered to con-
list of four round parts, with little divisions
between each. In the water of slimy matter,
found in leaden pipes or gutters, various kinds
c^ animalcules are discovered, and among the
rest, multitudes that appear to have a sort of
wheel-work, turning round in the manner now
described.*
The immense multitude- of these animalcules,
^ Those who wish a more particular description of
animalcales, may be referred to Adams's " Microgra-
phia lUuttrata" his "Essays on the Microscope/'
Leuwenhoek's " Arcana NeUura^** and Pritchard's
«
** Xatoral History of Animalcules/' where there are
hundreds of figures of animalcules of all forms delin-
eatsd.
134 THE MroRosropK and itr orjeots.
the strange forms they assume, the minute ai
delicate orgcinization of their bodies, and all tl
mar\'elous diversities of their existence, rend'
them objects of unfailing interest. In the coi
templation of these wonders of the divine wori
manship, indicating the probability of life as f
below the reach of the microscope as worlds ai
systems to which the telescope points are abo^
its highest range, who does not see that Omt
potence is as gentle as it is mighty, and as bom
tiful as it is universal ?
It will neither be uninteresting nor uninstm
tive to inquire, whether these minute living aton
are endowed with that faculty of thought whi<
is usually described by the word sagacity. M
Baker informs us, that a small quantity of tl
matter containing the hair-like animalcules ha'
ing been put into a jar of water, it so happem
that one part went down immediately to tl
bottom, while the other continued floating c
the top. When things had remained for son
time in this position, each of these swarms c
animalcules began to grow weary of its situatio
and had a mind apparently to change its quartei
Both armies, therefore, set out at the same tim
the one proceeding upwards and the other dowi
wards, so that, after some hours* journey, the
met in the middle. A w\s\v lo Vxvo^ Vvqst tJhe
THE MICROSCOPE AND ITS OBJECTS. 135
ifToald behave on this occasion led the observer
to watch them carefully ; and to his surprise, he
saw the army that was marching upwards open
to the right and left, to make room for that
which was descendmg. Thus, without confu-
sion or intermixture, each held on its way ; the
body that was going up proceeding in two col-
umns to the top, and the other journeying in one
phalanx to the bottom, as if each had been under
the direction of a leader. '' After viewing ani-
malooles in a microscope," says a writer, '' I was
in the habit of returning the drop which contain-
ed them to the vessel holding the fluid out of
which it was taken, washing it off the slider with
a little pure water. On one occasion, I looked
f\gatn at the sUder through the microscope, and
foand a little creature m a very small drop which
had been left behind. Feeling itself somewhat
confined, it attempted to get out of the drop ; it
went from side to side, and tried five or six places
in order to extricate itself from its confinement ;
but finding no opening, it placed itself in the
middle, and whirled itself roimd its axis like a
windmill, till the drop was quite evaporated, and
Uien, after a few throbs, it ceased to move. At
another time, I happened to be looking at the
spots in the sun, and was not a little surprised
to see one of them, as I sup^jQ6(Qd,ix^QWki^^Rxn^
13S TIIR »
iU disc. Tbis I soon found lo be a small animal,
about the eize of a mi(«, on one of the glasses <A
the telescope which I inclosed between Iwo c«i-
cave glasses. I afterwards watched its move-
ments through the microscope, and observed
that it seemed verj- desirous to free itself from
its coDfinement. It moved first to one poist
where there seemed a slight opening ; but finding
none, it tried other apparent crevices ; and when
at last it gave up its attempts, it returned to the
centre of its place of confinement. In these
cases, the little creatures seem to have reasoned
and acted as rational beings might have dcme in
similar circumstances."
Among those who stand foremost in the ranlc
of microscopic naturalists. Professor Ehrenbei^,
t« whom we have already alluded, takes the
lead. In various parts of the I'arlh he has
studied minute organic productions ; and the
results of liis persevering inquiries have beeo
given to the world. His researches, daring
BaroD Humboldt's last journey, extended to
more than fifty degrees of longitude, and four-
teen degrees of latitude. He went us far as
Dongola in Africa, and the Altai mountaina in
Asia ; and examined animalcules in a great vsr
riety of situations. He found them on Momt
HTSOBJF.CTB. I3»J
Irells of the Oasis of Jtipitei' Ammon, and at J
t considerable depth in Rime Siberian mini
^Boes entirely deprived of light.
All animalcules were once confounded i
the name of Infusoria, because they were n
irith, by their first discoverers, in water &
tag vegetable matter, or in infusions of vegetabl
lubstonces. But the propriety of a general ap-
pellation nill be apparent, when a due considera-
fion is given to the circumstances in which these
ttinule bebgs appear. It is an astounding yet
ir^-attested fact, that organized beings, poa
MBtng life and all its functions, have been dix ^
BOvered so small, that a million of them would
Oocapy less space than a grain of sand. The
absolute number of these "miniatures of life"
hx exceeds tliat of all other living creatures on
the surface of our globe.
Their reproduction is perfectly astonishbg.
En some instances, n single individual gives birth
to millions in a very short space of time. After
Qieir death, the accumulation of their shields or
bard out«r coverings, mixed up with vaHoos
earthy or flinty particles, produces layers of
fariouB earths and roclu. These become con-
■olidated by lime into clays, flints, and marbles,
a whiob the shape of thek a\\w\46 raA. 'i
iuaeters are so clearly lo \* ii^itmigN^
138 TiiK
FIg.«.
that the very sppcies can
determioed. The hones
which razors, penknives, a
other catting'
are sharpened, are made of a
Turkish stone, which is a
mass of the fossil comenngs
of animalcules. Tripoli, or rotten-stone, its
long bBen well knowri in the arts — being used
in the form of powder for polishing stones and
nieta.U. It has been procured, among other
places, from Bilin, in Bohemia; where a nngli
bed, extending over & wide area, is no lesa thfVI
fourteen feet thick. Immense mountfun-masscs
r.Misist of symmetrical bodies, between one fiw
thousnndth and one ten-thousandth of an huh
in di«raeter, articulated together in the form rf
rings, as in chalk ; or of Jilender threads, as<iii
limestone and the quartz of granite. An exact
oovinterpttH of this curious stnicture in Ihe
mineral kingdom is e\liihit«d in the vegetabis
by the moldiness of paste, and in the antinal hf
the creature called Gaillmiella fftruginea.
The tripoli just menljoned consists almOBt
entirely of an aggregate of nnimalcnles, in
widely-extended layprs, without any comiectil^
medium. A cubic inch of this substance -wcn^
THE inOROBCOPE AXD ITS OBJECTS. 139
millioiiB of these gaillonellse ; the shield of each
Goe weighing ahout one thousand one hundred
and eighty-seven millionth part of a grain. At
every stroke that is made with this polishing
powder, several millions, perhaps tens of millions,
of perfect fossils are crushed to atoms.
Even where the shields cannot he separated
in a distinct form, as in the consolidated nodules
of various flints, opals, and other suhstances,
troces of them and of similar remains are found.
It is scarcely possible to imagine the countless
multitudes of these beings which must have ex-
isted in former ages, for their very coverings to
have thus accumulated. It is peculiarly interest-
ing to trace such occurrences in progress at the
present time. Water, brought from a lake in
the island of St. Vincent, has been seen crowded
with the shields of races of animalcules at pre-
sent inhabiting it ; and the mud which is being
deposited abundantly at the bottom of the lake
IB stated by Dr. Carpenter, to whom we owe
the fact, to be almost entirely composed of
them.
Some remarkable appearances of the ocean
are to be traced to these Uttle creatures. In the
voyage of the " Beagle, on the coast of Chili,
a few leagues south of Conception, the vessel
one day passed through great bands of muddy
water ; a degree Bouth of Talpara'iso the same
appearnnce was slill raore extensive. Some of
the water having been drawn up in b glass, it
was found to be filled with living heings. Tbdr
shape was oval, and contracted by a ring round
the middle, from which proceeded the organs
of motion ; it was difficult to examine them,
for almost the int^tunt motion ceased their
bodies burst. Sometimea both ends buret iit
once ; somelimea only one, and a quantity o£
coarse brownish matter was thrown out. They
were ei:ceedingly minute, and quite invisible to
the naked eye, only covering a space equal to
the square of the thousandth of an inch." "In
one day," adds Mr. Darwin, " we passed through
two spaces of water thus staiiied, one of which
alone must have extended over several square
miles. What incalculable numbers of th*M
microscopical animals ! The color of the water.
as seen at some distance, was like that of •
river which has flowed through a red clay
district ; but, under the shade of the veesel's
side, it was quite as dark as chocolate, Tia
line where the red and blue water joined was
distinctly defined ; the weather, for some dv^
previously, had been calm, and the ocean
abounded, to an unusual degi-ee, with Uving
crefitures," The Luminous ap^eaisnca ^i^fnHi
ISB HICHOEiUOI>E AM) IT)i OBJECTS. 141
IB also partly accounted for by innuiuer-
ide multitudes of phospboresuetit animalcales.
In Sweden, on tliu aliores of a Iske near
inea, araet quantity of extremely -fine matter
, found, much like flour in appearance, and
died by tbe natives mountain meal ; it is used
t food, bwng mixed with flour, jind is nutri-
cniB. But nrliat is tliia mountain meal when
lined by the microscope ? Nothbg more
the shelly coverings of certain animalcules I
kB tlie animals perish, these coverings uccumu-
ite from age to age at the bottom of the waters,
Dd form a deep layer. This, drying on the
liore, or on places which are no longer covered
y water, assumes llie appearance whence it hag
■ names, each partiulc being the relic of a
ticroscopic animal,*
The minuteness of some animalcules is almost
loonceivable. Under the most poiverful mi-
roscope, they appear only as moving points, of
'hioh, by the use of the micrometer— an inatru-
lent for measuring very minute bodies — eight
ondred thousmid millions are calculated to
ccupy a cubic inch of the water in which they
oR«4der8 desirnua of furtlior information on tbis
itject, ma; lnj reforred to " CuriositieB of Animttl
A, wilb ivceDt DiscoverivB ot tVie 1A.\niovso^!'
btdbjtbe IteligioaB Ttaot aoeifii,; .
t
H2 THE MlUliOhC'Ol'E ANTJ I'J'S ulWEClS,
are found. Sup<;rior instruments, in rcfioeibnit
aud accuracy, would probably disclose creatnra
far inferior in sjee. Let it not bo supposed
tliat such Etatements are citrnvftgant and hase-
less. These are facts, which have been repeat-
edly observed ; nnd, startling as the statement
may be, it is proi'ed thnt> a drop of wst^l',
t«iiiuilcd by the smallest anlmalculeB, termed
monads, (to which we have already allodedi)
contains a number «quul to that of the whole
liiunau population of Ihe globe.
The p!teiiomena o/blooi!.
The blood of man and of land animals is
found by the microscope to consist of round rti
globules, floating in a transparent w&ter Of
serum. Dach red globule is made up of all
smaller and more trauspai'eot ones, and eaeli
of these ^ain, according to Leuwenhoek, M
composed of six globules still more minut« and
colorless, so that every common red globule a
compounded of at least thirty-six smaller ooMi
The diameter of a common round globule of
human blood has been found to be equal to the
omj thouBaiid nine hundred and fortieth part if
an inch. In order to view the blood with a
microscope, take a small drop of warm blood as
i from the vein, and, witlt the tip^^Jhk
'fcair peacil, spread it as thinly
idip of glass. It m»y also be diluted with a little
'Warm water.
CWcwiatioa. of tjus blood. — This wonderful
(phenomenon, the esisteuce of which was first
'ascertained by the celebrated Han-ey. about
the year 1610, was never actually witnessed by
Um, as miuroscopes were at that time
known. As regards microscopic life, it appi
to hare been first discovered in the water-
by Mr. William Molyneaux, in the yenr
Leuwenhoek, so much famed for Lis ekUl, has
given many illuHtmtiona and descriptions of the
method of emmlnmg it in eeis and small fishes.
In order to observe the blood circulating in the
reins and ai'teries, such small creatures as by
their transparency permit us to look through
tiidr external cuticle, and see what passes
within tliem, arc <6sl to be used. Such are
the frog, the water-ccwt, tadpoles, ctile, spiders,
mi some other insects. The transparent mem-
faiane between the toea of the hind foot of a
frog, is the object most commonly selected for
riewing the circulation of the blood, and in
this it may be seen distinctly and beautifully,
loth in the vems and arteries. A more sti-iking
xt than (his can scarceVy >ia 'va«.igms&, tst
more calculated to fiU ovit tooAs --s^ ^-
1
n of ihe divine skill manifested in ev«y
part of the organisation of the crentures of GwJ.
Fig. 46 exhibits the vesseb in which this tip
culation is performed, a a are the two toee of
n frog's hinder foot ; b, the thin memhiane be-
tween the toes, extended ; o c, the trunlu of iIh
arteries: d d, the trunk o( avevn-, -t^,&ttenei
<orf reina in the £dq membiane, VaV *w >i
HK JHCBOSCOI'E AND 1T8 OBJKCT8.
[es cireulatiag through them. The larger
arteries are distinguishable by a protrusion of
the blood at each contraction of the heart,
whereas the current passes through the veins
With an equal and Tinmtennitting stream. In
the finer and extreme branches of the arteries
this difference is not perceptible. The circula-
tion of the blood may also be distinody seen in
a Bmall tadpole, about an inch or three quarters
of an inch in length. This creature generally
lies quite still under the microGcope, and the cir-
culation is Eeen in the vessels of the tail, in the
fins on each side, and near the head. M. Leu-
wenhoek tells US', that in the tail of a fish not
more than half an inch in length, lie haa seen the
blood running towards the extremities through
arteries, and returning back again through veins
wluch were evidently a continuation of those
arteries, and of the same diameter with them.
Hb remarks, " It is easy to conceive how smaU
ihe tail must be, and yet in it there were sixty-
eight vessels which carried and returned the
lilood, and these vessels were far from being the
most minute of all, How inconceivably numer-
ous, then, must the circulaluais in, the whole ha-
mui body be I"
10
140 XBE MICKOSCOPE AND 1T3 OBJECTS. V
DeeerijJl'OH of the parts of some small ammalt,
(IS seen in- the microscope.
The flea. — This uflpopular little animal ap-
pears a very beautiful and curious creature when
examined by tbe microscope. With a common
compound glass, it may be magnified to the ex-
tent of eight or ten ijiches in length and a cor-
responding breadth. It is adorned 'with a curi-
ously-polished coat of armor, or iiard shelly
Boalea, neatly jointed and folded over each other,
and studded with long spikes, somewhat like the
quills of a porcupine. Tbe general appearance
of the animal is that of a beautiful piece of rt-
riegated tortoise-shell. Its neck ia finely arched,
and in shape resembles a lobster's tail. Its head
is furnished on each side with a beautiful, quick,
•nd round black eye, behind which
THE MICROSCOPE AND ITS OBJECTS. 147
unall cavity, ia which moves a thin film, with
many transparent hairs, forming, as is supposed,
ts ears. From the fore part of its head proceed
iwo little jointed hairy horns or feelers, a and b,
Ig. 47. Between these and its two fore legs,
3 D, is situated its piercer or sucker. This in-
cludes a pair of darts, which, after the piercer
bas made its entrance, are thrust farther into
the flesh, to make the blood flow ; thus is formed
that round red spot, with a hole in the centre
3f it, called a flea-bite. Besides its feelers, this
insect has six legs, four of which are joined at
the breast. When the flea intends to leap, it
folds up its six legs together, and then throws
them all out at the same instant, and thereby
exerts its whole strength at once, so as to
carry its little body to a considerable distance.
The legs have many joints, from each of which
proceed long hairs or bristles ; and each foot is
famished with a pair of hooked claws or talons,
that the insect in leaping may cling the better
to what it lights upon. It is interesting to no-
tice the surprising agility with which this little
creature can leap, as many experiments have
proved, a hundred times its length. Its pro-
digious strength is no less remarkable. It has
been made to draw loads, hundreds of times
heavier than its own bulk. Its muscles must
THE MICROSCOPE AStl IT8 OBJECTS,
therefore be very strong and vigorous. Hoff
weak and sluggish, ia proportion to Iheir siie,
must be the liorse, tlie cumel, and even the ele-
phant, when compared with this puny insect!
Ple.as are male and female, and they pass through
the same chftnges as the sillcworm. When their
oggs are hatched, they come out in the shape of
worms or maggots ; tliey afterwards put on tba
chrysalis or aurelia form, and when they isaoe
from this etatc they are perfect fleas.
2, Mites. — Mitea are very Gmall creature*
foimd in cheese, meal, and otlier substances. To
the naked eye they appear like diist in raoticm;
but the sharpest eye is unable to distinguiBh
their parts without the assistance of glasses.
By the microscope we. perceive that they are
aoimalB, perfect in all their members, and that
they perform all the offices of Hfe in as regular
a manner as those wliich are ten thousand times
larger. The mite is a crustaceous animalcule.
It has a small head in proportion to its body, a
sharp snout, and a mouth like that of a mole.
It has two smnii eyes, and six and sometimes
eight legs, each of which terminates in two
booked claws. Each leg has six joints, sur-
roimded with hairs. The hinder part of the
body is plump and bulky, ends in an oval form,
and ia coFered with a few long hairs, aomft flf
1
160 THE MICROSCOPE AND ITS OBJECTS.
tbem as long as the animal itself. Other parta
of the body and the head also have hairs. The
female lays eggs, and the young ones issue forth
with all their members entire. The diameter of
a mite's egg is about the diameter of the hcur
of a man's head, and m hundred such hairs are
equal to the length of an inch. It would take
ninety-one million, one hundred and twenty
thousand of these eggs to equal in size one
pigeon's egg. The mite is very voracious, and
is exceedingly tenacious of life. It has heen,
kept alive for months together without food. It
is represented in fig. 48.
3. Some curious species of small crustaceons
animals are found in the water of ditches. Two
of the most remarkable are represented in figs.
49 and 60, in the posture in which they swim.
Their legs are somewhat like those of shrimps
or lobsters, but of a more curious structure. In
size they are less than a very small flea. They
carry their spawn either on the tail or in bags,
as in fig. 49. They appear to have only one
eye, which is placed in the middle of the fore-
head. They are sometimes found so transparent
that the motion of their intestines is distinctly
seen through the microscope, with a re^lar
pulsation in a part supposed to be the heart
Another animal of a singular iorm \& T^^xosu^uted
TUE SHfKOSC'OPE ASU ITS OBJEt'TS. I^
fig. 51. It is found in infusions of vegeta-
bles, and in water that has stood some time un-
ered. This little creatine is in its middle
atate ; it was lately it worm, and will soon be-
come a gnat. It has a very large bead in pro-
portion to its body, wbich is covered with a
Bhell. It hfts several tufts of hair, two horns,
eitd a large mouth; The hinder part of the
belly consists of eight joints, from the midst of
which, on either side, issue small bristles. The
. is divided into two parts, very different in
their structure. One of them, a, has several
faifts of hair, hy which it can steer itself in the
water as it pleases ; the other part, c, appears
to be the ninth division of its body. Fiom the
part to the head appears a colored intestine,
through which the peristaltio motion is discerni-
ble. After having lived in the water its allotted
le, a remorbable change ensues. It assumes
a different form, and having cast off skin, eyes,
horns, and tails, it appears the insect of a dif-
ferent element. The most beautiful and elegant
plumage adorns its head, its wings are curiously
friaged and ornamented, it springs into the air
with astonishing freedom and swiftness, and the
creature which a few minutes before was an in-
hatdtant of the water, wovild. uiaw \a d\:Q«fted
if it were plunged into it.
1G2 THE UIC'ROSCOFK AND ITS OBJKCTB.
4. The etinga ofanimalt. — These are sbarp and
penetrating inBtruments, iritli which the t^ls of
wasps, bees, hornets, and some other insecta are
fumiahed, for defending themselves against thwr
enemies. The sting of a bee and of a wasp are
similar ; it is a homy sheath which includes twfi
bearded durta. The sheath tnpers to a very fiu
point, and near it is aa opening, tlirough which,
at the time of stinging, the darts are protruded,
One of them is a liLlle longer than the other,
and they penetrate alternately deeper and deeper,
taking hold of the flesh by hooks, till the wbole
stzng is buried in the woiwd, when a veoomoiu
juice is injected frona a little bag at its root,
which occasions an acute pain. The ehealh
with its darts is represented in fig. 52. If du
wounded person starts before the bee can diaof
gage the sting, it is left behind sticking in the
wound ; but if he can have patience to stand
calm and unmoved, the bee brings down the
lateral points, and clinches them round the shaft
of the daj-t, by which means the weapon is re-
covered, and less pain is given to the sufTerer.
5. The hairs of animals. — These supply
materials also for microscopical observation.
All bail's are found to be tubular, that is, they
consist of extremely minute tubes or pipes.
There is a great variety in the hairs of
THE MICROSOOPB AND ITS OBJECTS. 153
anirruJa when examined by the microscope.
H«ia taken from the head, the eye-brows, the
nostrils, the beard, the hand, and other parts of
the body, appear dissimilar, both in the roots
and in other parts, varying as plants do of the
same genus but of different species. They have
each a round bulbous root, which lies very deep
in the skin, and imbibe their proper food from
the adjacent humors. The hair of a mouse
seems to be one single transparent tube, with a
pith made up of a fibrous substance running in
dark -lines, in some hairs transversely, and in
others spirally. A bat's hau*, especially that of
the Indian bat, presents a most beautiful struc-
ture. It is remarkable for a series of scale-like
projections, arranged in the form of a whorl
around the central part, or shaft. In some hairs,
the succession of whorls resemble very much a
series of conical bags, placed one within the
other.
6. Scales of fishes. — The outside coverings of
fishes are scales, formed with inconceivable
beauty and regularity, and ai-e very curious ob-
jects for the microscope. Some are long, some
round, some square, some triangular, and others
of all imaginable shapes. Some are armed with
sharp prickles, as those of the perch and the
sole, while others have smooth edges. There is
I?
he beRj, T
likewise a great variety of scales,
same fish, for the scales taken from the
, the back, the sides, the bead, and other purtfl,
are different from each other. There is no woA
of art we can compare with their bcautJfuI me-
chanism. The finest needle-work Vhicli liM
ever been wi'ought cannot for a moment be put
in competition with the beautiful net-work, and
interwenvioga, and divarications which appear in
the contexture of these scales. The scales of
eels arc among the most i-emarkable. ISamj
imagine that these iah are without scales, on BO-
count of their being firmly imbedded in a thick
epidernial mucu$. In order to procure them, a
sharp knife must be passed underneath the ep.'
dermal layer, and a portion of it having been
raised, a few scales may be detached. They are
of an oval figure, and rather softer than those of
other fishes. To view the scales of any fish to
advantage, they should be soaked in water for a
few days, and then carefully rubbed, to clean
them from the skin and dirt which may adhere
7. The dust m llie mngs of {he wio(A and
butterflij. — On the "nings of these insecta ia a
fflealy dust, or down, which is n beautiful object
for the ;oicrosOftpe. The \inft& wtv '*» ■aoiwto
particles have been used of \a(e V<*« ^'^ \»si!to%
[eflniDg powers of simple lenses and acbro-
: combinaljons. The dust is easily removed
tom the wing by gently pressing it upon on ordi-
laiy slider, or upon a thin piece of glass, to j
'hich it will firmly adhere. It consista (^^|
Mthers of different shapes, mtli ten or twelfft^^B
iats on each, proceeding from a point, like the ~
IB^ of a circle, and terminating in well- defined
Rilnta at the other end. Those in one part of
e wing often differ from those in anothcjr part
of it. On its fringes, and near the thorax and
ihoulder, they have the appearance of hair rather
thaa of feathers. The feathers of the moth are
longer and more beautiful than those of the but-
terfly. But when some quantity of dust from
the wing of cither is laid upon a slider, or a thin
l^ltp of glass, under the compound achromatic
jnicroscope, with a power which will make the
feathei-9 appear two or three inches in length,
tbey present a variegated and splendid appear-
ance.
8. The ei/es of insects. — In all creatures, the
e ifl a atriking object ; but the eyes of insects,
so peculiar as to excite our highest admiration,
'KOXAd have been unknown to us without the as-
sistance of the microscope. On the heads of
ieellea, bees, w^sps, coTOi!noafiK.a, M\\a, iiasj^-
lea, batterSies, aod other inaeiU, tfta-"^ '^^'V**-
166 THE M.ICRO9C0PE AKD
ceived two protubernnces, which contain a pro-
digious number of small transparent hemispheret,
placed with the utmost regularity in lines cross-
ing each other, and resembling lattice-wwk.
These are a collection of eyes, so perfect^
smooth and polished, that, like so ouinj mirror^
they reflect the images of all external objects.
The image of a. caudle or a window<sash msy be
seen multiplied to an astonishing exteal. Fignre
£3, taken from Adams's " MlerograpMa," exhi^fgi
a representation of the eye and some other parU
of a di'one fly. Tlint half of the heraispWe*,
c D E, c D £, which looked lowaxiavvs V^^ww^
observed to be smallir Omvu fcc o<k« V«K,
c E, whicL looked upwards and side-
The surface of these heraisplieres wns bo
I EiBODth and regular, tliat in each of them the
as nble to discover a landscape of
I those objects which lay before the window, part
of which was a large tree, whose trunk and top
be plainly sow. These little hemispheres have
each a minute transparent lens in the middle,
which has a distinct optic nerve ministering to it.
While other aniraals are obliged to turn their
^es to objects, the fly has eyes nearly all around
it. The number of the hemispheres or globules
in the drone-fly was reckoned to be fourteen
thousand, being seven thousand in each eye.
Leuvenhoek reckoned six thousand two hundred
and thirty-wi in a silkworm's two eyes, three
thousand one hundred and eighty in each eye of
a beetle, and eight thousand in the two eyes
of a common-fly. In a dragon-fly he reckoned
in each eye twelve thousand five hundred and
forty-four lenses, or in both twenty-five thousand
and eighty-eight, placed iu a heitangulnr position,
each Ions having six others around it. A por-
tion of these transparent hemispheres may be
seen by allowing the rays of the svm to shine
upon the eye of a dead fly, when placed under
B microscope on a slip of gWa,
I
158 THS MIOBOSOpPB AND nt 0BJB01B.
Vegetable substances.
Vegetable nature presents to us an imi
field for the employment of the microscop(
innumerable beauties and wonders which,
out this instrument, would never have bee
covered or imagined. Our limits prevent va
doing more than briefly noticing a few exai
1 . The farina ofjlowers, — This appears
naked eye a kind of powder, which is fou
the pendant tops of almost every flower
color is various in different flowers, but its
Q ture is invariably the same in plants of the
■ ti . species. The microscope has shown us thi
powder, in former ages supposed to be a
excrementitious and unnecessary part o
plant, is produced with the utmost care, i:
sels wonderfully contrived to open and disc
it when it becomes mature ; and that thei
pistil, or seed-vessel, in the centre of the £
ready to receive the minute grains of this
der, either as they fall of themselves, (
blown out of their httle cells. From nun
* : experiments, it is found that on this the fe
of the seed entirely depends; for if the
vessels are cut off* before they open and
shed their powder, the seed is improlific.
intended for the nucroscope, the farina sho
i t
■L .
I
i . •
■ I ^
gfttliered duiing a diy sunny day, and gently"
brushed off witli a soft hair pencil on a, pieco of
whiK paper, and put upon a elip of glass to be
applied to the microscope. A collection of tli6_
most remarkable kinds of farina of difTercnt flon^J
era will amply repay the care and attention of B^|
who delight to examine the works of God. j|
2, The leaves of plaiils and Jlowera. — The
leaves of trees, shrubs, or flowers, are found to
be full of innumerable ramifications, which con-
vey the perspirable juices to the pores for their
discharge. The fibres of the leaf do not stand
in even lines from the stalks, but always in an
angular or circular position. Tliis arrangement
tends to the more erect growth and greater
strength of the leaf, and also to the security of
its sap. M. Leuwenhoek, having torn a leaf of
box to pieces, that he might examine it thor-
oughly, computed one side of it to contain one
hundred and seventy-two thousand and ninety
pores ; and as the other side had the same
number, the total amount of pores in a box leaf
.was thus ascertflincd to be three hundred and
forty-four thousand one hundred and eighty.
Leaves in general exhibit a great variety of beau-
tiful ramifications. Tbe back of a rose-tree lea^
but espedally of a sweet-brier leaf, looks aa '^m
^pered with silver. A sag^e leaf appears jl
160 THE MICROSCOPE AND ITS OBJECTS.
if tasseled with white silver thrums, and embd-
lished with fine round crystal beads, fastened by
little foot stalks. The little globules which ap-
pear on these and other aromatic plants are sup-
posed to give rise to their fragrance. The back
of the leaf of the English mercury plant loob
as if rough-cast with silver, and as if all the ribs
also were set round with white transparent balls.
Fig. 54 represents a magnified view of the sweet-
brier leaf. Fig. 55 is the sage leaf magnified.
The leaves of plants and flowers are indeed a
striking comment on the words of our Saviour :
** Consider the lilies of the field, how they grow ;
they toil not, neither do they spin ; and yet I
say unto you, That even Solomon in all his glory
was not arrayed like one of these." Matt. vi.
28, 29. So beautiful and delicate is the fabric
of the leaves of plants, and especially of flowers,
as seen in the microscope, that it infinitely ex-
ceeds in these respects all the finest pieces of
workmanship that art has ever produced. The
threads of the most delicate ribbon, under the
microscope, look hke the coarsest rope-yam, and
the silk itself like the substance of a conunon
door-mat. But the more we magnify the leaves
of plants, the more do we recognize the hand of
Him who fills the universe with light and every
Aower with beauty.
THE MICB":*^"^^
113 OBJtUIB'
I
■^Sl^,'
J
162 THE MICROSCOPE AND ITS OBJECTS.
3. Transverse sections of plants, — ^These sec-
tions are procured by cutting a small branch
transversely with a very fine sharp instrument,
so as to take ofif a slice nearly as thin as the hu-
man skin, which then may be viewed as a trans-
parent object ; while the air vessels, sap vessels,
and pores of the wood, will be seen in their
variegated figures, incalculable numbers, and
beautiful arrangment. The writer has several
of these sections, one of which he can never
behold without the gi-eatest admiration. It is
little more than a quarter of an inch in diameter.
It consists of a number of concentric circles or
divisions in its diameter, with an immense num-
ber of radii proceeding from the centre to the
circumference, and pores, or sap and air vessels
of different sizes, distributed in beautiful sym-
metrical order throughout the whole. From a
calculation made, it appears that there are not
less than one million two hundred thousand
pores, or the openings of tubes, contained within
its circumference. And all nature is full of these
" marvelous works !"
The following figure represents a portion of a
transverse section of the root of mallows. The
diameter of the section was about three-eighths
of an inch, and the one-eighth part of that sec-
Uon was cut out from it, and placed imder the
IHB >UCIlOfiC01-£ AN'D ITS OfiJKlTS. ltJ3
He. K.
* * ft *
microscope, wlien it appeared as represented m
the figure a s shows the skin c d the bark,
or all that part of the root which answers to It
E r, the common Ijmphcducte , a n, the pithy
part of the root ; i k, more lympheductsi in both
which the black holes arc the air vessels. It is
Dext to imposeible, however, to represent in an
engraving alliba openings or vesaela which ap-
pear in the section of a plant, when viewed
through a powerful microscope, as new apertures
164 THE MICKOSCOPE AND ITS OIUKCIB.
i'
1
■J
are seen by every augmentation of the lighl
I power of an achromatic glass. It may ak
observed, that the configuration and the nui
of openings or vessels are all different from
other in the roots and branches of different t
(\ so that in this respect, as well as in every o
there is an immense profusion of beauty
variety in tlie works of God.
A great number of other microscopic ol
might have been described, had our hmited {
permitted, but we shall briefly mention onl;
following. By the microscope it has been
covered that there are scales on the human
so small that, according to the calculatio
Leuwenhoek, two hundred of them may be
ered by a grain of sand. The perspirable
ter is supposed to issue between these 8<
which lie over the pores through whicl
watery humors exude. The pores of the
are exceedingly numerous. If a slice of
upper skin be cut off with a sharp razor, as
as possible, and a second slice from the
place be immediately applied to the micros
innumerable pores will be perceived. M.
wenhoek supposes that there are one hui
pores in a line one-tenth of an inch long,
inch will, therefore, contain one thousand
row, and a foot twelve thousand. Accordii
i:
4
I
. t ■■
1.1
. "if.: '
.-» V
y ■
oompuLaticm, a foot square must have in it
one hundred and forty-four niilliona of pores ;
and if tlie superficies of a middle-sized man be
fourteen square feet, tliere will be in his skin two
thousand and sixteen millions of pores. If the
band be well washed, and examined ^vith a mag-
nifying lens, in the palm, or upon the ends or the
first joints of the thumb and fingers, innumera-
ble ridges, parallel to each other, will be found.
On these ridges, pores may be perceived, lying
in rows ; and when viewed through a good glass,
ev«ry pore seems a little fountain, with the per-
flpiratjon st^inding in it as clear as water ; if
wiped away, the perapiration will be found im-
mediately to spring up again.
The threads with which a spider weaves its
web are worthy of our attentive consideralion,
on account of their extreme fineness. M, Leu-
wenhoek, having dissected the body of the long-
est spider he could find, and nicely examined
each part, at ]ast discovered a vast niunber of
instniraents, as they may be termed, from which
the spider draws threads of various fineness ;
these thread vessels he judged to be at least
four hundred, lying, not close t(^ether, but in
several distinct clusters. Having laid a spider
on its back, so that it oovii ^uA ?,'OT,Vft-^"*&s*i-
oiit, with a very fina pmt ot ^«\ts«B>, ». ■&:««£
166 THE MICROSCOPE AND ITS OBJECTS.
that he perceived sticking out of one of the
working instruments. . At the same time he saw
a great many other very fine threads issuing
from the insect's trunk, which, at the distance
of a hair's breadth or two from the body, were
joined together, and made thick threads. *Some
of these filaments were so extremely fine as al-
most to elude his sight, though he made use of
his most powerful glasses. Hence it appears
that the threads of a spider's web, which to the
naked eye seem to be single, do really consist
of several plies, some of which are so exceed-
ingly fine, that Leuwenhoek thought that one
hundred of them put together would not make
one-hundredth part of the thickness of a hair
of his head. Ten thousand, therefore, of the
fine threads of a full-grown spider are not so
thick as a human hair ; and if we add to this,
that four hundred young spiders, when they
first begin to spin, are not, one with another,
bigger than a full-grown one, and yet that each
of these spiders is provided with all the instru-
ments of the old one, it will follow that the
smallest thread of a young spider is four hun-
dred times smaller than that of a great one;
and if so, then four million of such threads are
not so thick as the hau- of a man's head, a fineness
quite astonishing, and beyond our conception.
THE MICROSCOPE AND" ITS OBJECTS. 167
Test ohjecta, — About the year 1826, Dr. Gor-
ing discovered that the structure of certain
bodies could be readily seen by some micro-
scopes, but not by others. These bodies he
called test objects. In the course of his experi-
mentsj he was led to the conclusion that there
were two distinct powers in a microscope, name-
ly* defining and penetrating, and that an object-
glass might possess the one almost to perfection,
and yet be totally devoid of the other, or might
be perfect in both. At present, however, it is
the opinion of the most celebrated opticians that
the terms definition and defining power are the
only expressions requisite to be employed to de-
note the good or bad qualities of any microscope.
The test objects now generally employed for
ascertaining the merits of any achromatic com-
bination may be divided into three kinds, namely,
hairs of animals, scales from the wings and bodies
of insects, and the siliceous coatings of recent
and fossil infusoria, — those of the latter kind be-
ing the most difficult of all to define. The fol-
lowing fist contains a few of the test objects to
which allusion has been made : —
Hairs. — The Bat. — The hair which forms one
of the test objects is obtained from the species
of bat before mentioned, inhabiting some parts
of India. The principal parts of the hair that
fonn tt test of the defining power of a Iifllf-inch
object-glass, are the delicate points, or scale- Kks
projectjons, that surround the iipper edge of
each whorl, which should be slioirn osoeedingly
sharp. In some of the species of English bate,
the whorls are arranged in a spiral form. Moim
huh: — The hair of this little animal differs va.-
terially both in structure and in size from tlutt
of the bat. In some parts of the hair the in-
ternal structure is cellular, there being three or
more cells in each row,_the color of the hair de-
pending upon the greater or less amount of the
black pigment contained in the cells. Wlien
viewed with a power of one or two hundred
diarapters, all the light parts shoiild be shown
distinctly from the dark, and the line of separa-
tion of the two correctly defined. When viewed
as an op»que object, tbis hair is veiy beautiflil.
Hair of the demiestes, — This very remarkable
hair is obtained from the larva of a small beetle,
commonly met with in hacou, hams, and othei'
dried animal substances. It is covered over with
brownish hairs, the longest specimens of which
should be selected. When one of these is viewed
with a magnitying power of two hundred diame-
ters, the upper part may be said to consist of a
shaft and expanded extremity or head. The
part of the shaft, x&xx tW V,«ed, la
1
vided witli several larirer and more obtuse spines,
forming u knob. This very beautiful hair i
forms a good teat of the defining power of a
half-inch object-glass. The hairs of Che r
the rabbit, and the Bquirrel, are aiso used ps i»
objects.
Scalei on (lie wiriffs or bodieg of incwf*.-"
ffipparchta Janira, the common meadow brown
butterfly. The scales of this butterfly conast of
lon^tudbal stria;, with n number of brown spots
of irregular shape. When the magnifying power
is increflsed to one thousand two hundred diame-
ters, tiie brown cells are made more evident!
Poiitia Bratsicit.the common cabbage butterfly,
— This scale, like that of the former, ia provided ol
its free extremity with a brush-like appendage.
Its striaj are longitudinal, and with a power of
live hundred diameters, it appears to be com-
posed of rows of little squares or beads. Sciiies
of Podiira, the common spring twj. — The body
and legs of these Uny creatures are covered with
scales of great delicacy. The surface of them
appears covered with immense numbers of wedge-
shaped dots, an-anged so as to form both longi-
tudinal and transverse wavy markings ; when
minified one thoasaad two hundred dinmetei^
the scales are seen to stand out boldly from tl
surface ; at ilio upper part of the scale, t
\
170 THE MICROKOOPE AND ITS OBJECTS.
also project beyond the edge. These insects
abound in damp cellars, where they may be
seen running or skipping on walls. Scales frcm
a ffnafs toing. — ^These, when magnified five htm-
dred diameters, exhibit very bold longitudinal
bands or striae, which project beyond the end in
the form of spines. In the membrane between
the longitudinal striae there is sometimes an ap-
pearance like the watering in silk. Scale of
MorphQ Menelaus, — A scale of this splendid but-
terfly, when magnified five hundred diameters,
exhibits strongly-marked longitudinal and very
delicate transverse striae, the former frequently
bifurcating. A half-inch achromatic object-glass
should show them readily. Several other tests,
besides those above enumerated, have been dis-
covered by modern microscopes, which our con-
fined limits prevent us from noticing.
CompaHson of the works of nature and art —
There is nothing that more conspicuously dis-
plays the perfection of the works of God than
a comparison of them with the finest works of
art. The contrast between the one and the
other is exceedingly striking, and hiunbling to
the pride of man. His best performances, when
examined by the microscope, appear coarse and
shapeless ; but the more closely and clearly we
are enabled to inspect the works of God, the
171
; apparent is their supreme excellence. This
be exemplified by a few illuatratjons. The
t of an exceedingly email needle, highly
ihcd, when Tiewed with a high magnifying
er, appears neither ronnd nor flat, but full
olea and scratches, and as broad and blunt
le end of a poker, and looks as if it had
I hammered on the anyil. On the other
1, the sting of a bee or of a gnat, the pro-
is of a butterfly or flea, appear, when ei-
led by the raioroscope, to be formed with
most surprising beauty, and with exact regu-
y. The sting of a bee shows a polish with-
the least flaw, blemish, or inequality, and
. hi a point too fine to be discerned; yet
is only the s/aatk of instruments still more
ed. The following figure represents n piece
Eceedingly fine lawn, as it appeared through
microscope. From the great distanced W
]
172 THE MICROSCOPE AXD ITS OBJSCfTO.
tween its threads it looks like a lattice, and the
threads themselves appear coarser than ropes.
Compare this with any leaf of the forest, or
grass of the field, under the same magnifying
power, and a most striking contrast will be per-
ceired.
The small dot or point, which is generally the
mark of a full stop or period, when greatly mag-
nified appears to be rough, jagged, and uneven
all round its edges, and very far from being truly
round. The smoothest and most exquisitely-en-
graved lines and points, when examined by the
microscope, seem like so many furrows and holes,
or like daubings on a mat made with a blunt ex-
tinguished brand. On submitting to the micro-
scope the edge of a very keen razor, it appears
as broad as the back of a thick knife, rough, full
of notches, and furrows, sharper in some places
than othei*s. Compare these works of human
art with the operations of a puny insect, directed
.by instinct, or the wisdom and intelligence of its
Creator, and the contrast appears most striking
and admirable. A silkworm's web, examined
by the microscope, appears perfectly smooth and
shining, everywhere equal, and as much finer
than any thread which the most dexterous spin-
ner in the world can make, as the thinnest twine
h smaller than the thickest cable. The web
THE M10R0600P£ AJiD ITB OBJECTS. Il3
woven by a spider is still more delicate. Every
thread of it is many thousands of times smaller
than a human hair. In short, every minute hair
and fibre on a flea, a gnat, a fly, and other in-
sects, is not only smooth and beautifully polished,
but, when magnified thousands of times, appears
as sharp at the point as a needle.
Thus smk the works of man when placed in
comparison with the works of God. Wherever
the microscope is applied, there beauty, order,
and perfection are displayed. In all the innu-
merable varieties of insects which fly through
the air, swim in the waters, or crawl along the
earth, symmetry, proportion, and uniformity,
are perceptible. Their bodies, heads, wings,
feet, and other members, are embellished as
with rubies, diamonds, gold, silver, and pearls ;
they are colored with azure, green, yellow, red,
and vermilion hues ; yet in all there is nothing
gaudy or incongruous. How unutterable the
Perfection of which these are the creations !
Metlwd of using microscopes, — 1. In applying
the microscope to use, examine in the first
place whether the glasses be clean ; if not, they
must be carefully wiped with very soft leather,
taking care not to soil them with the fingers,
nor to place them in an oYXvs^'^ ^^j^sa^ksoL.
2, The object should be \ko\x^\» ^ ^^^»3l "^^
174 THE MICROSCOPE AND ITS OBJECTS.
centre of the field of view as possible, for th^e
only it will be exhibited in perfection. In a
compound microscope, the eye should be moved
up and down till the situation is foimd wh^e
the largest field and the most distinct yiew of
the object are to be had. 3. A small mini-
fying power should always be first used, by
which means an observer will best obtain an
exact idea of the connection and situation of the
whole. In general, it may be remarked, that
there is no advantage in examining any object
with a higher power than what shows it dis-
tinctly. A moderate power affords a greater
light, and shows objects more clearly, than the
highest powers, although sometimes these are
required. 4. The eye should be protected
from all extraneous light, and should not re-
ceive any but what is transmitted through or
reflected from the object. 5. According to Sir
D. Brewster, the best position for microscopical
observations is when the observer is lying hori-
zontally on his back. This, he says, arises
from the perfect stability of his head, and from
the equality of the lubricating film of fluid
which covers the coniea. The worst of all
positions is that in which we look downwards,
vertically. If we stand up and look horizon-
tally, parallel markings or lines will be seen
i
THE MICROSCOPE AND ITS OBJECTS. 175
most perfectly when their direction is vertical,
heing the course in which the luhricating fluid
descends over the cornea. 6. Every part of
the view should be excluded except that which
is under immediate observation. 7. In every
case of microscopical observations, homogeneous
yellow light, procured from a monochromatic
lamp, should be employed. 8. In viewing
opaque objects, an opportunity should be taken
wheir the sun shines of making his rays strike
upon the surface of the object. In this way
we may view to advantage the body and the eye
of a fly, the fibres of a peacock's feather, and
similar objects. Or, a broad convex lens, about
three inches focal distance, may be so placed as
to throw the light of a lamp upon the object,
the surface of which would then be distinctly
visible. The best mode, however, of viewing
opaque objects is by means of a contrivance
called the Lieberkuhn, from the name of its
inventor. This consists of a concave silver
speculum, highly polished, in the centre of
which is placed a magnifying lens. This specu-
lum has a small hole in its centre, and may be
applied immediately below the object-glass of a
compound microscope. For this purpose the
speculum must be placed at the end of a small
tube, to slip over the tube which holds the
176 THE MICBO&COPE ASD IIS ^NUaCIBw
object-gbse. The hgtii proceeding fiom tlie
minor faUs apoo tlie specalnm, and is reflected
peqiendicnlarij on the upper surfiMe of the
object.
It seems almost trite and needless to sav,
•
that the discoTeries which we have been con-
skieringy equally with those of the telescope,
demonstrate the existence of God, and -teach
us lessons of confidence in him, by showing us
that there is rothing too minute for his notice,
or too humble for his care. Why is it, then,
we may inquire, that any should habitually
live as if he could nowhere be seen in "the
thinsfs that are made ?" Whv is it that he
should be so Uttle thought of, acknowledged,
and adored, when his glory is reflected by every
object in nature — from the blazing sun to the
atom which floats in its beam — from the moun-
tain to the flower which blooms beneath its
shelter — and from "the great and wide sea"
to that drop of water which is as an ocean to
the numberless and invisible creatures which
it contains? To these solemn questions we
have a reply in the words of the great reformer,
Luther: "Had not man sinned," said he,
**how would he have recognized the glory of
1
THE MICROSCOPE AND ITS OBJECTS. l77
God in all his creatures, and have loved and
exalted his holy name ; so that in the smallest
flower he would have acknowledged the al-
mighty power, wisdom, and goodness of God !"
Max has sinio:d, and therefore it is that *' God
is not in all his thoughts."
It is sometimes said, as if it were a maxim
not to be disputed, that *' nature leads us up
to nature's God." It is not true. Man has
SINNED, and he " will not seek after God," till
he knows more than nature, with all its light,
can teach him. He is surrounded, as we have
seen in the preceding pages, by proofs of wis-
dom and power, infinitely surpassing the highest
efforts of human intelligence and skill. This
may be confessed. There may be admiration,
and even gratitude, awakened by these displays
of the divine perfections, and yet there may be
no knowledge of God. Such a recognition of
him is better than atheism, better than indif-
ference, better than absolute forgetf ulness ; and
yet it is compatible with mournful ignorance of
the moral perfections of God, and with the ab-
sence of all desire to retain him in the mind.
Man has sinned, and he needs the word of
God to teach him how ^vine holiness and
justice may be harmonized with mercy in his
pardon and restoration to bappinesa, Vla ^&
n
178 THE laCROSCOPS AND ITS OBJECTS.
conscious of estrangement and danger; and
before he can know God in nature, so as to
delight in him, he must know him in Christ as
a Father, " reconcihng the world imto himself/'
Has the reader, then, we may appropriately
ask, been thus reconciled? If not, then, "as
though God did beseech you by us, we pray
you in Christ's stead, be ye reconciled to God.
For he hath made him to be sin for us, who
knew no sin ; that we might be made the right-
eousness of God in him." 2 Cor. v, 19-21. The
telescope and the microscope, whose revelations
we have been considering, may be said to lend
emphasis to this appeal. In the views which
they open to us of the majesty of God, they
proclaim his infinite power to bless those who
love him, no less than his awful ability to
punish such as obstinately reject the proclama-
tion of his grace. How dreadful must it be to
die at enmity with so great a Being ! — ^how de-
lightful to be his adopted child, through faith
in Christ ! Now, then, while it is the accepted
time, may the reader, if he has not yet done so,
close in with the pro£fers of his pardoning love !
THE END.
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